De-catting vs. removing a silencer from exhaust on 2.0 TS

I'm trying to decide whether to remove the cat from my exhaust or remove one (or more) of the silencers. The car is a 99 GTV TS (phase 2 155bhp) so doesn't have the pre-cats or lambda censors as far as i know. The previous owner already has a BMC air filter installed in the standard airbox. Car has 78k on the clock if that makes any difference i.e. the cat being clogged up over the years making it more restrictive?

What I'd like to achieve is the best overall gain in sound, throttle response, driveability and power between the two methods. Although I don't want the exhaust to sound too loud or boomy either and have to keep the tail pipe standard to keep on the better side of the law and not annoy the neighbours or look like a chav.

Now i know that removing the cat will make my car fail an emissions test so i won't be making any modifications until after my car has done it's N.C.T. test (Irish MOT).

Price really doesn't come into it either as a very good friend of mine is a metal fabricator by trade so i will hopefully be getting him to knock up a straight through pipe as a direct replacement which i can then re-install for any further N.C.T.'s etc. for the price of a few cans of carlsberg.

In my mind I'm leaning more towards removing the cat rather than a silencer as i presume it would be more beneficial overall. Just thought I'd get the opinion of a few of the more knowledgeable folk off here before i let Rory loose with the angle grinder!

Morning chap
check out my post below.did all what your asking and very happy with the results.plus mines got a k&n on it.
hope this helps
john

http://www.alfaowner.com/Forum/tunin...-decating.html (GTV ts exhaust mod plus decating)

These chaps are helpful Alfaholics: Stainless Steel Sports Exhausts and I think their system is highly rated. They also have a review on their website.

You can buy the sections separately, which is handy.

I have the transverse silencer taken out and it sounds lovely, if a bit boomy. The Alfaholics guy's leave the trans silencer in and replace the rest with free flow cat/silencers.

I was wondering whether to take the middle silencer out and replace it with the alfaholics middle section (free flow silencer ) but I think it'll make it too loud, so am leaving it. They are very helpful and said for power + sound that their cat replacement section is better than replacing the middle silencer.....

Originally Posted by activeservo

These chaps are helpful Alfaholics: Stainless Steel Sports Exhausts and I think their system is highly rated. They also have a review on their website.

You can buy the sections separately, which is handy.

I have the transverse silencer taken out and it sounds lovely, if a bit boomy. The Alfaholics guy's leave the trans silencer in and replace the rest with free flow cat/silencers.

I was wondering whether to take the middle silencer out and replace it with the alfaholics middle section (free flow silencer ) but I think it'll make it too loud, so am leaving it. They are very helpful and said for power + sound that their cat replacement section is better than replacing the middle silencer.....

Hi

yeah there system's are nice but i have'nt got that kind of cash.plus if i can do it myself.why pay loads for the same type of system.im very happy with the sound and it rev's lovely.
plus you can get sports cats on Ebay for around £80. 200 cell

regards john

I have fitted the Alfaholics middle section, and it sounds very nice.Not at all loud just nicer, although i do still have the standard back box for now.The Alfaholics back box is very expensive at £350+VAT so will price up a custom back box before buying.

Removing the cat will free up more power than removing the silencer. Your car will have a lambda sensor fitted, even if it has no pre cats. In my experience, cats don't block up gradually, so much as suddenly; you'll know if its blocked because you won't be able to get more than 3000rpm out of it!!

I made a decat pipe (straight through pipe) for my old 145 QV which I was running with an OE Alfa system.

I found that the baffles were failing in the rest of the system as a result of the decat pipe. I do not think that there were significant gains to be had from it and it was significantly louder.


However, I had a scilenced decat and full stainless cy-box (peco) system fitted to my 2.5 V6 156 and saw a gain of around 8bhp. Be warned though, it was LOUD.