working on a tpi setup and was wondering if the catalytic converter is necessary. i know some fuel injected systems work best with the back pressure, but i'm in south carolina and there are no emission tests. don't know if i should go through the and expense of purchasing the cat or just do without.

 

the cat is not "needed" for the car to work, but its still illegal to not have one, its a federal deal, just because you are not inspected for one doesnt mean it doesnt have to be there.

However, you most likely will never be hassled for not having one.

 

i think as far as back pressure goes, youll be alright. removing that cat will free up so much flow, and deffinatly give your car a more agressive exhaust tone. the muffler and all the bends should provide plenty enough back pressure. almost everyone i know or can think of, run without cats on thier thirdgens, actually just about any car lol. even i dont have one, instead i have a custom made y-pipe going into 3" intermediate with flow master out back. oh and hooker super comp headers. id say my car runs pretty stout.

 

i would suggest keeping it hooked up if you have everything smog legal still.
i bought my 5.7 iroc with a high flow cat already installed but the dumbass didnt weld it in and didnt hook up the smog pump to it, so it has 3 BIG exhaust leaks, and it runs like crap at low RPM.
unless you can tell the rest of the system to completely ignore any of the smog systems (i hear you have to burn your own chip) i would say just get a free flow cat and hook up the smog stuff.
then you can tell everyone "hey, im making this much power AND its smog legal! what now b*tches!"

...you can leave out that last part if you like. hahaha.

 

^ What this guy said.