1. pets
2. cats

MASERATI 4200 EXHAUST VARIATIONS & LOTS OF DETAILS....
...or “THE ULTIMATE EXHAUST GUIDE”
– by (Modest) Gordon Norris
Variants and Identification:
Before rushing off to buy a new exhaust system, or parts thereof, for your 4200, please be aware there
are some significant differences between cars from different years and markets. Add to that some cars
may have been retro-fitted with different systems for compliancing, performance modification, etc.
you really need to identify the type of system you have at the outset. Some of the parts are NOT
interchangeable. I've included 2 diagrams from the parts listings, (these are from an 05 car listing, but
they are all similar across all years, including GS's, except for the valved rear boxes in GS's and other
detail differences between years) Below are some pics to assist in identification of the 2 main variants,
which are commonly referred to as UK/Euro-spec/4 bolt flange, and US/Canada/2 bolt flange systems.
You could have either system irrespective of the cars' origin.
The easiest way to determine your system is to look at your exhaust manifolds/headers. (parts 12 & 13
in figure 1, parts 1 & 2 in figure 2)
Fig. 1 Above: UK/Euro Spec 4 bolt flange, and below pics of corresponding manifold.
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Fig. 2 Above: US/Canada Spec 2 bolt flange, and below pics of corresponding manifold.
All cars have twin exhausts with 2 CATs in each exhaust pipe (a primary CAT and a secondary CAT);
4 CATs in total. (Please note, the primary CATS are also sometimes referred to as “pre-CATS”.) As
you can see, the UK/Euro-spec manifolds have long sweeping primary pipes, an angled 4-bolt flange
where they mate to the first section of exhaust pipe, and the primary CATS are at the start of this first
section after the flange under the car,. whereas in the US/Canada manifolds the primary CATS are a
part of the manifold, (the big bulge in the middle of the manifold/headers) have a 2-bolt flange that is
in line with the first exhaust section, and a straight pipe leading to the secondary CATS. (The
secondary CATS are the same and in the same position for all versions.)
Design Problems:
The standard CATS on the Maseratis (and Ferraris for that matter) are not well designed; not what you
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expect from a premium manufacturer. They are fragile, ceramic-cored, and very restrictive with 400
elements in the primaries and 600 elements in the secondaries. Most good CATS, including those in
quality after-market systems such as the Larinis are now metallic-cored (much more durable) and
much higher flowing with only 200 elements, and yet retain high efficiency as CATs. The ceramiccored CATS are prone to breaking up internally after impact damage (where the pipes hit a speed
hump or similar) and the bits flow downstream and block the secondary CATS. You may have heard
of the even worse scenario where the ceramic fragments from the primary CATS get sucked back into
the engine on the overrun, destroying the very expensive engine catastrophically. This seems to be a
rare event, but is much more likely in the cars with the US/Canada spec where the primary CAT is part
of the header and so much closer to the exhaust ports. I have not read of it happening in a UK/Euro
spec system. (NOTE: Just because a car originates in UK/Europe does NOT mean it necessarily
has the UK/Euro exhaust set up, especially if it is a GS)
The standard pipe sections after the flanges are flattened on all cars to clear the steering rack in a bid
to have some reasonable ground clearance. This is seen as a flow restriction point, and is not an ideal
design point. However, as the pipe sections are widened significantly where flattened, the overall
cross-sectional area is not as bad as many make out, and the CATs remain the main source of
restriction. However, the flattened sections do pose another liability in that they are easily
squashed/creased even more with contact/impact with speed humps, etc., some to the point of near
occlusion. The Larini design is clever in that the flattened section is replaced with 2 small tubes each
side to maintain clearance, but preserve flow and offer more resistance to flattening/damage. Virtually
all other designs on the market seriously compromise ground clearance, and can lead to worsened
liability of CAT break-up from impact. Nearly all primary CAT failures in these cars appear to be
impact or scrape related, and virtually all secondary CAT failures are due to clogging from
failed primary CAT debris.
Pros/Cons and Options:
The UK/Euro manifolds, by not having the primary CATs stuck in the middle of them, are a much
better design flow-wise than the US/Canada manifolds which have their large and restrictive primary
CATs in the middle. The UK/Euro manifolds also have larger diameter tubing as well (51mm or
2inches), and resemble semi-race designs, so offer optimum flow. They have a comparable design,
but with less joins and a better collector than the expensive (approx. USD $6000) Larini Racing
manifolds, pictured below:
Above: Larini Racing Manifolds-comparable to the standard Maserati UK/Euro headers, but
with a 2 bolt flange to mate to the rest of the US/Canada system, and a pinch at only US$6,000!
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Whilst the UK/Euro-spec vehicles do have the primary cats at the start of the exhaust just after the
flange, it is a smaller CAT than the US/Canada primary, and may even have fewer elements, but I can't
find out for sure. The primary CAT is just as fragile and vulnerable to impact, or perhaps more so,
being at the exhaust low point, but less likely to have fragments sucked back into the engine, and is
much easier and cheaper to replace as it is in the same piece of pipe as the secondary CATs..
So if you have the UK/Euro-spec headers you are fortunate indeed from the performance viewpoint,
and doubly so as you can more easily delete the trouble-prone primary CATs! This should include all
2002-2004 UK/Euro cars and most 2002-2004 AUS delivered cars. Unfortunately, after 2004, due
to tightening emission requirements, and to ease costs via parts rationalisation, nearly all the cars
including UK and AUS delivered cars defaulted to the unfortunate poor-flowing and expensive
US/Canada spec. This includes most of the GS's irrespective of market, but for some odd reason, not
all GS's and post-2004 cars. So once again I stress: check what system you have.
If you have the UK/Euro spec, the trouble-prone primary CATs can be easily eliminated as mentioned
above, using the Larini sports CATs, or other after-market equivalent which deletes the primary CATs
but retain the secondary CATs in a free-flow form, to keep it all legal. That way you have just one pair
of high-flow CAT's, and a completely legal system. The de-cats could also be used for a complete
CAT-free system, but you run the risk of running foul of the law, and you may get a check engine
light, as well as a lot more noise! Larini's SILENCED de-CATs are another option here to get the noise
down in a full de-CAT system.
If you have the US/Canada spec, you've got a much bigger problem if you want to delete the
troublesome primary CATs. Some have cut the primary CATs out and welded in substitutes, (such as
the FD stand alone CATs), (pictured below) or even cut open, cored out the originals, and welded shut
again, but it's hardly a DIY job and would need an expert welder/fabricator. If the replacement CATs
are metallic rather than ceramic-cored, it does remove the problem of CAT break-up, and possible
catastrophic engine failure.
Above: FD (Formula Dynamics) stand-alone weld-in Sports Cats; NOTE:These are NOT Larini.
The US/Canada CAT replacement is also tremendously expensive for routine replacement, due to the
CAT-in header design, the whole manifold needing to be replaced when the CATs wear out or break
down.
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It is feasible to replace the US/Canada manifolds permanently with the UK/Euro manifolds, but
remember you will need to also change to the 4 bolt flange follow on section and relocate the Lambda
probes to their new positions. (The latter is easy as Maserati seem to be generous with the wire length
on most probes. There are 2 probe types: One in front of the Primary CAT, (part 182837) and one
behind the primary CAT (part 191412) and these Part. Nos. are identical across all cars, all exhaust
variants and all years). I have read of one owner who did the conversion from US to UK spec
manifolds successfully, and with noticeably better performance as expected, but I can't find the thread
now, and I would wonder whether he had the ECU re-flashed at the dealer, as the ECU parameters are
different for the 2 systems. I just don't know the answer to this at present, and that really bugs me!.
Apart from that, if you don't want to go to the trouble of replacing the US/Canada spec primary CATs
and manifolds, and just want increased performance, then you can go to the Larini (or similar) sports
CATs, but you'll still have a 4 CAT system, or go to the De-CAT pipes, which gives you a legal 2 CAT
system (retaining your original primary CATs as the 2 CATs). As mentioned above, the silenced deCATs are another option to keep noise down. Neither of these will give the same performance increase
you could expect from the UK/Euro options, but it is what the yanks do, so results will be as reported
on the US forums and FD site.
Larinis and their Purchase:
As you may have gathered I tend to favour the Larini CAT systems. Not all manufacturers are
forthcoming with the internal make up of their CATs, and many have cheap Chinese internals.
Magnaflow in particular have CATs that are allegedly inoperative/break down after a very short time.
On the other hand, Larini seem to be well engineered, offer a lifetime warranty, and they have
considered the lambda probe positions carefully, and minimised the potential for a check engine light,
compared to most other manufacturers. They offer both UK/Euro-spec 4 bolt flange and US/Canadaspec 2bolt flange sports CATs and de-CATs., and preserve ground clearance as mentioned earlier. See
pics below:
Above: Larini Sports Cats – UK/Euro-spec on the left and US/Canada-spec on the right; note
the different flange angles and flange designs (4-bolt vs 2-bolt).
However, I was surprised that Jeff at FD, even with his great knowledge of these cars, knew little
about the UK/Euro-spec cars and their systems. But then again in his defence, and by his own
admission, he had never seen one, whereas Noor at Performance Italia in the UK (FD's UK agent)
knew about both systems in detail. I sent Jeff some info, so he knows a bit more now. Jeff said he
could obtain the UK/Euro parts, but it would require a pre-order and there would be a delay, whereas
Noor usually had stock and could ship right away, as the Larini factory is local to him.
Fabspeed also don't seem to have any knowledge of the UK/Euro-spec despite (erroneously)claiming
their system fits all cars worldwide. Being US based they again have never seen a UK/Euro system.
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Not really confidence inspiring: Imagine ordering and finding it didn't fit!
Interestingly, Performance Italia's prices for Larini are better than FD's, and even more so when you
factor in the current excellent AUD-GBP exchange rate, but this is almost certainly because the Larini
Factory is actually based in England. Noor says he ships regularly to Australia and shipping cost for a
set of sports Cat pipes is about GBP100. I think he would be amenable to a group buy from what
I've read on the UK forums. Both Noor and Jeff seem to offer better pricing than through the local
Larini agents, more than can be accounted for by exchange rates and shipping.
Other Exhaust Bits:
The rear boxes or mufflers define the tone of the exhaust to a large degree, as well as volume to some
degree. There are many on the market and each has it's devotees. It is a matter of taste. There are
plenty of sound samples on YouTube, but the quality of audio on many videos is questionable; just
keep that in mind when listening. Camcorder mics aren't usually very good, and iPhones even worse.
Brands include Tubi, Fabspeed, Magnaflow, Kreissieg, Capristo, Mille Miglia (Australian!),
Supersprint, and Larini, amongst others I can't remember. Listen to them on YouTube. The stock
Maserati boxes are allegedly made by Tubi. The aftermarket Tubi systems, (and several others) seem
prone to causing an annoying drone at highway cruising speeds, especially with a full X-pipe fitted..
Larini are one of the few to offer valved rear mufflers to preserve the GS “dual-tone”, and allow nonGS owners to have valved rear boxes if you wish. With the Larini valved boxes, with the valves open,
the sound is comparable to a stock set of rear boxes, but with them closed it quietens it down a little.
This is ideal if you modify the CATs and have increased sound volume: you can therefore quieten it
down for cruising and in heavily built-up areas where you want to be more discreet, not to mention
RBT checkpoints and the like.
Central Muffler, X-pipe, or H-pipe? Just to keep everyone on their toes, Maserati fitted 2 types of
central muffler/resonator on the 4200 series. All non-US cars, including GS's share the same Central
Silencer, which is a muffled X-pipe (part 187826). The US Coupes also have the same part, but the
US GS's have an un-muffled true X-pipe (part 204476). I note from one of Jeff's replies to Craig that
he seems to be unaware that non-US cars DO NOT have the US style X-pipe (unless they've been
modified. I believe some Euro cars were actually ordered this way also, or perhaps they were Friday
parts-bin specials.)
The different X-pipe in the US was done by Maserati for 2 reasons: Firstly, it was an attempt to regain
some HP on the US GS's which are optimised for the lower octane fuel available in the US and suffer
a HP drop compared to Eurospec cars, and secondly they could get away with it because the noise
regulations in the USA are more relaxed than many other countries...it is the home of hot rods and
Harleys after all....
The US X-pipe is reported to liberate up to 8-10 extra ponies, but there is no reason any aftermarket
brand should be significantly better or worse than any other. I'm just a believer that if you buy all
one brand, everything is likely to go together better. But there are many who run hybrid exhaust
systems.
Using an X-pipe also saves the weight of the standard muffler, saving up to 10 kgs. In fact a complete
stainless sports sytem can be expected to save between 20-30 kg in total front to back. That's
equivalent to adding another 5 - 8 HP on its own, and any weight reduction helps handling & braking
also, even if only marginally. It also means you can eat more maccas and not worry about it affecting
the performance of the car!
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For many, the X-pipe ups the noise volume too far, and many fit it only to replace it later with an Hpipe. This allegedly gives almost the same gains as an X-pipe, (but I've never seen back-to-back hard
dyno figures) and has the advantage of being quieter with less free-way drone.
Lambdas & Thermocouples: All the cars run dual Lambdas (oxygen sensors) on each side, before
and after the primary CATs. The secondary CATs are unmonitored, but do have a single thermocouple
for each side on all cars until somewhere through 2004 when they were phased out. (The
thermocouples monitor Exhaust Gas Temperature, and are often used in racing (also known as an
“EGT sensor”) and CAT temperature.) Some say they were deleted because the incidence of primary
CAT break-up leading to blocked secondary CATs was very high, and the consequent high secondary
CAT temperature caused the thermocouples to trigger a check engine light too often, or even cause the
car to enter limp mode. I don't know if this is true, but after 2004 the thermocouples were deleted.
As noted earlier, Larini have given a lot of consideration to lambda placement, and if you go to the
Performance Italia or FD sites and read the extended blurb attached to the Larini Sports CAT sections
it will explain the development of these components in more detail.
KEEP OLD BITS!:
On a final note, it is wise to keep all the old exhaust bits unless you are really pressed for storage
space. Why? Because the fun-police (RTA, EPA, etc) may just pull you over if you are making a lot of
noise, and on testing fail your car. I had this happen to me years ago in a modified FIAT X/19 with a
custom exhaust, that was quite mild. It failed the roadside test by 1dB. Luckily I had the old exhaust,
so when I reported for re-testing, it passed without problem; I then went home, put the custom exhaust
back on, put the pass certificate in the glove-box in case I was pulled over again, and drove around
without incident ever again. With all the Harleys echoing around the countryside at ear-splitting
concussive volume levels, it was just another example of revenue raising, and I was unlucky.
The Maserati system is all bolt-on, so a “quick-change” back to stock is relatively easy if necessary.
Without the original parts, it could end up being a catastrophically expensive exercise! To that end, if
you have someone fit the exhaust for you, be sure to talk to them about this before hand, and ask them
to try and avoid damaging the old components when removing, and keep them aside for you. A lot of
places will just cut off the old and discard otherwise.
That's about it for now. I'm sure I'll remember something I forgot later...
Hope all this helps. CHEERS!
Gordon (“amazerati”)
January 2012
(Could the Mayans be right, and the end is nigh on 21 December 2012?
Better drive hard now to make the most of it...just in case…well “that's my excuse officer...”)