I was thinking about putting in a midpipe after some searching dicided against it. Anyway's i was going to weld the outside of the cat flang and grind out the weld on the inside to give me a little more breathing room. I noticed when carring my cat around that it was making rattling noises, like a rock was in it, after some shaking i recieved presents. I haven't done any welding yet but, I'm sure this isn't a good thing. With out a ported wastegate i can't really put the midpipe in so where does this leave me? I know you guys will ask what mods i have
Pettit ecu, hks dp, and a farly gettoed exhaust (curtisy of my car's ex owner), i have a apexi AVC-R that i haven't gotten around to yet, as well as a greddy FMIC. Would i need all of these to support a midpipe or should i just bite the pullet put the stock cat back in and save up for a high flow? Here are some pics of my getto exhaust, and parts i recieved from my cat.
Stock flang welded to a 3in exhaust.

I ground out the inner weld lip

Yaaaa presents

 

Buy a used stock cat for $50.