RoW Exhaust - aftermarket system position of cats

[Ranfurly66]

Hi

I've searched on the forum and can see a few posts that refer to this but haven't answered my question.

I have a MY2004 6 speed S RoW spec (New Zealand car). I have been looking online at several systems (Fabspeed and SpeedTech mainly), either a full system including the exhaust manifold/headers back or just the mid pipes and rear muffler box.

I have got a bit confused re what I should be looking at as I had a look at my car and from what I can see it only has 2 cats at the rear (just before the rear muffler box), it doesn't have cats just off the stock headers.

The aftermarket exhaust systems from the US all seem to have the cats (sport cats) sitting on the headers and the rear cats get deleted.

I'm unsure if I can use the US exhaust systems on my car as the O2 sensors are routed to the rear cats and if there would be a drama to route them to cats positioned further forward by the headers. Just got a quote for the Fabspeed system (glup!) it is expensive.....

Thoughts/advice greatly appreciated.

Cheers

[jb92563]

I'm thinking that if you should probably acquire the US headers with the integrated CATs and then you could transfer the sensor connections to those and then use the 2nd CAT delete and Mufflers.

The trick is to keep the CATs & sensors somewhere in your muffler system so that you don't have to deal with the code issues.

Perhaps the Racers know of a way to eliminate the CATs completely and keep the ECU happy.

Do you still have to meet emission checks or will this be a track car?

Another option is a CAT back system where the CAT stays put and you just replace the muffler.

[edc]

Just buy a European spec one. There are loads about. You should have plain headers and a pair of manifolds between the manifolds and silencer and have a pre and post cat lambda.

[Ranfurly66]

Hi

Thanks. I'm working my way through it just spoke to the workshop service guy and he's said it is an EU4 car (only 2 cats at the rear). It is a street car and I want to keep CEL light issues to a minimum/nil so I'd look to keep cats on the car.

So you're right. I have 2 options:
- full system headers with sport cats or possibly mid pipes with rear sport cats (trying to find out if the system I'm looking at has the O2 bungs on each side of the rear cat). It is the expensive option with possibly some HP gain, maybe, who knows.
- Just replace the rear muffler and have improved noise. The OEM system is so quiet! Quite a bit less $$$ to be spent.

My main issue with putting on sport cat headers is whether rerouting the O2 sensors from the rear to the front. Does that cause any dramas getting the O2 sensors forward - will they go that far?

Thanks

[edc]

Why bother looking at all these options when you don't need to? On my last one i changed the manifolds and silencer and kept the standard cats. So far this time on my latest 986 I have the stainless same manifolds and 100 cell sports cats. I'm still deciding what to do for the silencer. Have a look at boxa.net as there are more owners there with the same spec cars running different exhausts.

[Steve Tinker]

Ran.....
This is what you can do with your ROW spec car - the same as what I have done here in Australia.

1) Replace the original exhaust manifold (headers) with something like Deluboz Parts (Top Speed Auto) sell in the US - strait swap with small HP gain higher up the rev range and a slightly harder sound.

2) Replace the cats with delete pipe from same supplier. This is illegal if cats are required in NZ. You will need to weld in stubs (supplied by Deluboz) into delete pipes to screw in O2 sensors which normally screw into the cats. I just got the local welding shop to do this - less than an hour - cost $60-00. Definate HP increase and much better sound above 3,500rpm.
I retained rear silencer (muffler) to control drone.

Che @ Deluboz ships to this side of the pond and I have had no problem with my system in 3 years of it being on the car.
Hope this helps.

[Ranfurly66]

Hi

Thank you for your comments and ideas. I'll sit back and process the different options - I need to do further reading and investigation.