I measured my resonator and it measures just a little over 21 inches so now I need to buy a cat to pass inspection. I've searched and I can't find any that big except from overstock.com but I've heard many negative reviews about them. Where could I get a cat that big?

 

U don't really need same size cat. If ur jus looking to make it pass jus jump on eBay n find any1 that will fit an fc. Jus make sure its not a really cheap one jus melt.

 

Then either weld it on urself if u can n got the tools, if not jus take it to muffler shop.

 

^^ ditto make it fit!

 

Why do you need a new cat? The one you have wont fit? or is it bad?

 

I have a resonator and I doubt it'll pass emissions with that.

 

I have a custom exhaust and i would need the same size because if its too small, it wont reach to be connected/bolted on and if its too big, it wont be able to fit in between the exhaust components.

 

By "custom", do you mean you picked parts from different brands or do you mean it was fabricated for your car?
Rx7store.com has a bolt-in with the racing beat header and corksport's bolts to a stock cat.
Otherwise, you'll need a core and take it to a shop. They can add lengths of pipe and flanges to make it fit.

 

Universal cat,some pipe,some flanges..
some Guy that can weld..DONE!

 

just buy 2 cats

 

This! Buy a cat and put weld some pipe on it so it fits in the spot you need it too.

 

I would go towards the not so mainstream exhausts that are out there. I've tried to find one just like mine and never found one that looked the same.

 

I REALLY dont want to go the welding route as I plan to put my resonator back on after.

 

you're missing everyone's point.. leave the flanges and make a replaceable cat with the same dimensions as your resonator!

basically meaning build your own slip in/out cat, most any muffler shop will know what you need if you tell them you want to retain ALL the exhaust flanges you have.