i work at a race track, and honestly it dosn't really make a huge diffrence, but even scca miatas have resonators, or other restrictive devices.

your car will sound like a pissed off weed wacker, and rattle your windows from 4,ooo+ rpm's and did i mention sound like crap. my gf's accord exhaust fell off at flex pipe and there was some hessitation but all in all, the car was fine, it could still go up hills, and pass but it just sounds like shit pops everytime you let off gas ect.

if you want a little twanger go right ahead, if you want a nice exhaust note keep your shit on there, even if you just throw a pipe through the cat (bypass) and a resonator it will sound 100x better

hope that helps in your decision