Hi all, recently got a 3"de-cat and fitted it soon as. Then noticed that the Hayward system from cat back is only 2.5" :-(
Spoke to a garage and they recommend a full 3" as they rekon its restrictive as is. Anyone agree with this, and if so, would there be any benefit to a 3" system??

 

A lot of conjecture on this.

Some people advocate that a 2.5" is good for upto 400 or even 450bhp! Beyond this, it's worthwhile going to 3" to do away with any potential restriction.

I personally have a full genuine 3" system i.e. inc. all flanges/unions, as I didn't want to take any chances with a potential restriction, etc. But I'm 'only' running 342bhp at the moment though.

 

This is depend on more factors,if you have good 2.5" will be OK/or should be for 400bhp,but if you have not effective 3" exhaust you have same problem again...
I'm running 2.5" and seems will be OK for 400/450bhp,my mapper said is OK/or should be OK for my needs(400bhp-450bhp)


Jura

 

Yeah, the actual quality of the system and attention to detail counts for a lot.

 

with that power id advise a quick check of the plugs!

 

lol at first I thought "Eh?"... Then I saw the poster!

Funny you should say that though, as the car is due it's BIG 45k cambelt service soon, and I'll do the plugs and everything else on the SSS as a matter of course.

It'll be IRO 800 big ones though, I reckon.

 

3 inch system's supposed to be louder than a 2.5.

 

 

Cheers guys. As I said before I have an unknown decat, but Hayward and scott system from cat back. I was told these are pretty good??? If I was to go for a full 3" system any recommendations? Thank you