I see that a lot of guys gut their cats. One thing I know about gasflow is that changes in cross sectional area increase flow resistance. When gutting a cat, weld a section of straight tubing inside the shell to make the cat 'invisible' to the exhaust gasses, thus helping flow. It also eliminates that strange resonance that a big mid-exhaust empty chamber can add.

I only ever did this on a Chevette and a Saab a long time ago, but they did sound a little better afterwards.

 

gutting a cat is not only pointless but stupid.

there's absolutely not "gain" in power by replacing the cat with a pipe or gutting it. and if you're really concerned with the cat robbing power then get a bullet cat.

it's illegal to run with no cats for a reason. the cat changes noxious fumes into much less harmful fumes. changes them into water and carbon dioxide.

 

I dont agree with that, an extra obstruction of air flow in the exhaust, I mean im not doubting that the gain is probably very small, but who knows maybe im wrong! My cat was completely clogged in my 94, and didnt have the $ for a new cat, so I just gutted it. Worked out great!

 

I actually agree with Severous that it is a poor idea to gut a working cat, and now that I'm not an ill-informed high schooler anymore, I wouldn't do it. However, since I see that some still do so, I figured they might as well be doing it right. I assume the only guys who gut the cat and participate here must have a car that is tuned so that it destroys the catalyst, but they need to pass visual inspections only. If that were the case, I could understand. I sure didn't mean to imply the practice is smart of cool. Its not.

 

I pollute enought with my other vehicles, what was the difference if the camaro did it too? The car was tuned right after the cat was gutted, so I dont know whats right or wrong, I just know the clogged cat sucked!

 

I put a pipe in place of my stock cat and gained nothing at the track. My MPH was the same as with the 120k mile cat. Now I stink like exhaust every time I drive the thing. I will be putting the cat back on shortly.

 

Or you could have just waited till you had the $400 for the pacesetter LTs and offroad y pipe.

 

dont know about yall but i replaced my original cat with a straight pipe and sold the cat to the muffler shop for 65.00. scrap people around here are buying the used cats up like crazy. muffler shop said their was good money in used cats.