Center decat noise question
 

On an otherwise standard UK classic exhaust, does swaping the center cat section for a pipe section with no resonator or silencer make any difference to the noise levels produced by the car?

Thanks

It won't make any appreciable difference to noise or performance. The backbox will make the biggest difference, followed by the downpipe/cat assembly. Assuming the front cat is in good nick then passing emissions test at MOT should be fine.
What's your reasoning?
Kevin

Its a bit of a long story so stay with me.

The car is a PPP MY00. I ran it it with a magnex center section instead of the PPP center, this increased the noise to a level where my good lady wife would tut and complain constantly pretty much ruining any drive out in the car..! So I got an STi 5 standard back box and managed to open out the tail section to improve flow. The power difference is marginal between the PPP back box and the STi 5 one, I was told by a number of tuners that the cats are the restrictions followed by the back box last. The standard back boxes aren't that bad. The car is now quiet as standard with the Magnex silenced center and STi5 box. I thought that fitting a straight through center with no silencers or resonators would give a little more noise back.

Does that make sence, probably not.

Alternativly I could get a PPP center section and refit the PPP back box, I'm thinking this should be quieter than the PPP back box and magnex silenced center.

Argh...!

I put a straight through magnex centre section on mine and it made no difference to the sound whatsoever. Then i put a blitz backbox on. now that made a difference!