I was wondering whatare the demensions on the catalytic converter, inlet and outlet holes. Is the out let hole size the same as the size going to the 3 bolt flange, thanks.

 

Its the same in and out. I believe it is 2.5" for both. The exhaust then drops to 2.25 behind the muffler as the exhaust gases have cooled down and become more dense thus taking up less space.

 

PV=MRT Do da Do da........ Gotta love gas law. Seems to me, that a 2.5, or 3in pipe wouldn't hurt anything......

 

Ok thanks, also, im asking this for my friend, if you remove the cat and put a straight pipe in, do you have to put a dummy o2 sensor in behind the cat or can you leave the regular one in?

 

Considering that it is against US Federal law to remove a functioning catalytic converter... Depending on where you live, you won't pass inspection without one either...

Your PCM will complain if it isn't there. The O2 sims are getting MUCH harder to find now as well.

As far as the size of the exhaust pipe, I don't think you would hurt much if you were to go 2.5" all the way out. But 3" without engine mods would be too large. The exhaust would slow down too much and start to stack up. You want to keep the exhaust moving as fast as possible and as hot as possible all the way to the tail pipe exit. This will maximize the effects of scavenging. Get too large and scavenging will not take place.