My custom cat-bypass job and a couple of videos

ecarca

ecarca

Junior Member
Messages
320
Congratulations on the purchase!

There are 2 things:

1. You need to know if you are Euro Spec or US Spec for the cats. It's simple: you need to look under the car to know if your primary cats are in the headers or on the pipe after that. If you are US spec, with the first cats in the headers, then you can use Fabspeed bypasses. I have a set for sale btw. I could not use it because I am "Euro spec", with both sets of cats in that pipe after the headers. There will be no CEL because only the first cats are monitored and they replace the second set.

2. You need to check if you have the central muffler or not. GS delivered in USA did not have this muffler, they had a X-pipe instead. I removed the central muffler on mine with the X-pipe from Fabspeed (it fits all versions).

All the rest of my exhaust: intermediate pipes and rear valved mufflers is stock.

I think it's the perfect balance and compromise for sounds but it is a matter of taste. For some it will not be loud enough and for some it will be too loud.
 
pamisa

pamisa

New Member
Messages
9
Thanks very much ecarca! I am enjoying every moment of it so far during the second day of the ownership.

I appreciate your reply above on the clear explanation. Mine is a Euro Spec I would assume as it is a RHD vehicle. US spec cars should have been all LHD I would think. However, I will check again as your comments above. Assuming I am a Euro spec I guess if I wanted mind to sound like yours, then I should order the X-pipe from Fabspeed and in additional I would have to get a custom made bypass here locally. And I'm happy to hear about the CEL as well which is a good thing.

To be honest I like mine loud and I feel yours certainly does the job for me!

ecarca said:
Congratulations on the purchase!

There are 2 things:

1. You need to know if you are Euro Spec or US Spec for the cats. It's simple: you need to look under the car to know if your primary cats are in the headers or on the pipe after that. If you are US spec, with the first cats in the headers, then you can use Fabspeed bypasses. I have a set for sale btw. I could not use it because I am "Euro spec", with both sets of cats in that pipe after the headers. There will be no CEL because only the first cats are monitored and they replace the second set.

2. You need to check if you have the central muffler or not. GS delivered in USA did not have this muffler, they had a X-pipe instead. I removed the central muffler on mine with the X-pipe from Fabspeed (it fits all versions).

All the rest of my exhaust: intermediate pipes and rear valved mufflers is stock.

I think it's the perfect balance and compromise for sounds but it is a matter of taste. For some it will not be loud enough and for some it will be too loud.
Click to expand...
 
mjheathcote

mjheathcote

Centenary Club
Messages
9,038
pamisa said:
Mine is a Euro Spec I would assume as it is a RHD
Click to expand...

Can't assume at all. There are many UK RHD and Australian RHD cars with US spec exhaust manifolds, it certainly appears that it was a case what was available for the production line at the time, especially with late cars.
 
adam01

adam01

Member
Messages
1,079
True that ^^^

Ned to check each car , not difficult and can be done without having to lift the car
 
ecarca

ecarca

Junior Member
Messages
320
pamisa said:
Thanks very much ecarca! I am enjoying every moment of it so far during the second day of the ownership.

I appreciate your reply above on the clear explanation. Mine is a Euro Spec I would assume as it is a RHD vehicle. US spec cars should have been all LHD I would think. However, I will check again as your comments above. Assuming I am a Euro spec I guess if I wanted mind to sound like yours, then I should order the X-pipe from Fabspeed and in additional I would have to get a custom made bypass here locally. And I'm happy to hear about the CEL as well which is a good thing.

To be honest I like mine loud and I feel yours certainly does the job for me!
Click to expand...

You're welcome. Not all RHD are "Euro spec", this is why it is tricky. For instance the OZ models are "US spec" for the exhaust, or at least some of them. This is why actually using "US spec" or "Euro spec" does not make too much sense ;)

You have to double check to be sure, it's easy if you pay attention to it: you notice it right away.

Yes, then you get an X-pipe and do a custom job for the bypass. Or you could get the Larini bypass that is state of the art, since they have a version for the Euro one. It replaces your first cats by high flow cats that they put in place of the secondary ones but it is very expensive. Their X-pipe is the same price as the fabspeed one though.

You could also try to have your shop do their design for the bypass but it requires special machines/skills that not every shop has.

Cheers
 
ecarca

ecarca

Junior Member
Messages
320
More of it (shot this afternoon), I already watched that about 100 times, I can't get enough of it. It's a bit more high pitched from the cabin but so throaty and good from the outside:

[video=youtube;T3v55c_sHu8]http://www.youtube.com/watch?v=T3v55c_sHu8[/video]
 
BennyD

BennyD

Sea Urchin Pate
Messages
15,006
That sounds nice. If you want a crisper, harder edged sound you need to get the rear boxes modified. It will nearly double the decibel output and you can still run the valves to quieten it when required. However, so far so good!
 
scociu

scociu

Junior Member
Messages
36
The title of the thread made me wonder: Is anyone here running a full decat system? I mean both pre-cats and main cats removed and replaced with straight pipes.
 
mjheathcote

mjheathcote

Centenary Club
Messages
9,038
scociu said:
The title of the thread made me wonder: Is anyone here running a full decat system? I mean both pre-cats and main cats removed and replaced with straight pipes.
Click to expand...

Tempted.
I have a front pair of original pipes considering cutting out all the cats.
Not sure how you would get on with the lambda sensors though.
 
ecarca

ecarca

Junior Member
Messages
320
BennyD said:
That sounds nice. If you want a crisper, harder edged sound you need to get the rear boxes modified. It will nearly double the decibel output and you can still run the valves to quieten it when required. However, so far so good!
Click to expand...

Yes, it is already properly loud as is. Regarding the valves, for some unknown reason they don't work anymore. I think I opened a thread about it someplace. They used to... At some point when they didn't I found at a vacuum pipe was disconnected from the valve on the muffler. This said, plugging it back did not make it work again...

So I am always running it with valves open, which is perfect :)

I would not be again modifying the stack boxes but could only do that if I had my vacuum valves work. Since I'd like to keep the "standard volume" the same as now.
 
ecarca

ecarca

Junior Member
Messages
320
scociu said:
The title of the thread made me wonder: Is anyone here running a full decat system? I mean both pre-cats and main cats removed and replaced with straight pipes.
Click to expand...

I think there was someone doing it, at least in the USA. They got some issues though from what I remember and put the front ones back in.

In my opinion, it is already very good with the second pair removed and allows you to keep it "clean" while having already gained most of the power you need. The best alternative is to use high flow ones to replace the front ones, or to ditch the front ones and keep a pair of high flow ones in the mid pipes. But then you need to extend your O2 sensors wiring. Same solution as Larini and I think fabspeed has a solution to but for US spec exhaust only.

Cheers
 
scociu

scociu

Junior Member
Messages
36
Thanks for the info. I have the EU cat layout, with all 4 cats on a single section and i am looking for decat options that will allow me to revert to the original setup. Initially i considered replacing the section with straight pipe, no cats, but it looks like i will have to consider adding a pair of sports cats in there to avoid potential CEL issues. I run my Alfa with all 4 cats removed and it was one of the best mods i made, no CEL light whatsoever, but i don't have any experience with how this would work on the Maserati.
 
C

Chrisbassett

Member
Messages
3,909
If you're not worried about the CEL then straight-through is fine, as long as you can put some cats back on for whatever emissions check your country imposes. Mine had a single sports (200 cell) cat per bank, and there were no issues with CEL's from the lambda sensors.

The noise level was acceptable. To me that is, not sure about those around me.
;-)
 
Contigo

Contigo

Sponsor
Messages
18,376
Louder than Benny's? :D

[video=youtube;SHV5QHDZTPc]http://www.youtube.com/watch?v=SHV5QHDZTPc[/video]
 
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