i have been told that a cheap way to bypass a cat is to knock or push a pipe/bar through the exhaust thus opening up the honeycomb structure. can this be done? also what is in the design of a sti back box that makes it soooooo quiet even tho it has a big bore.

You need to be a bit careful here. The last time anyone on here mentioned cruelty to cats, the thread nearly caught fire.

I've been thinking sort of the same thing.

I've got a STi embossed tailpipe backbox kicking about in my garage. I was thinking about taking it to the local welding company and asking them to cut it open, take out the insides and put a stright through pipe inside.

I assume it would be like not having a backbox fitted, performance wise etc.
Or is there something nasty that could happen ?
Apart from your ears bleeding from the noise :D and annoying the neighbours.


Kevin
:)



[Edited by kevin stanton - 7/13/2002 11:25:47 AM]

there must be a load of sound absorbing material in the sti box maybe u can remove all to get a more powerful bbox? as for the cat is it a honeycomb mesh structure?

I have never done it with a scoob, but once encountered an old Cavalier 16v with a cat that had broken into three bits and was making horrible rattling noises. Pushed the bits out with a metal bar. Rattling stopped. Car went noticeably faster. Fuel economy improved about 10%. However, when the "empty" cat box was replaced with a Magnex de-cat centre section, it went even better

Yes, it is kind of a honeycomb structure.

Phil