Has anyone tried back-to-back dyno tests with a 3" 100CPI race cat/without a cat?

I'm seriously considering getting a race cat.

John,

I had Blueflame fit a 2.75" 100cpi race cat,they really are tiny compared to the standard unit !
Didn't have back to back tests done but I could feel the difference and I also had to increse the gain on my Apexi to achieve the correct boost. Also at MOT time it was still a struggle to get it to pass, had to take the car out for a cat warm up drive and then load up the electrics to get it to pass.
Hope that helps ?

I got a decat pipe made up and took it off, just goes back on for MOT's now

Interesting. Not sure whether to give it a whirl as I have seen some dyno printouts (not on a coupe) where the car only lost about 10BHP which isn't too bad but haven't heard of anyone else doing comparisons

My general need is to make my exhaust quieter as well as I can't do most tracks as my exhaust is approx 104dB so I thought I could kill two birds with one stone. Alternatively I could just get a centre silencer I suppose.

It does silence it a little, probably the same as fitting an extra silencer.
If you think about it, removing the standard cat and fitting a decat pipe usually gains around 10-14bhp so fitting these so called sports cats doesn't really gain much, you cant beat a decat pipe no matter how bad it is for the enviroment or how illegal they are

Here's a couple of pics just so you can see how small they are:

Side View
Cells View

The Supersprint decat pipe is slienced and might be an option. About £90 new I think.

I dont think its the 3" diameter John is looking for though Strike.

You're right Jimbo, forgot it's only standard diameter. I guess H&S may be able to make something up also.

I do already have a straight decat pipe.

Hi John,

I did have 3" metallic race cat. I can't say any difference in power, what I could have with old GT28RS. I took it away, because I couldn't pass exhaust emission test. It cooled down too quickly.
But the noise reduction with it was quite clear, if you need some dB lower noise, that's the one.
Rather I use extra silencer than cat to have less noisy car .

- Jari -