Exhaust Question

I'm getting a new exhaust system for my celica, but i just found out that no brand makes catback system except for a TRD kazuma which would be illegal and too loud. My question is should i make a custom exhaust for my car or stick with an axle back ? My interest is all about performance. How much hp the axle backs makes from ? GReddy, HKS, Invidia, Tanabe, TRD ? My last question is, would a resonator drop the kazuma DB in order to put it street legal ?

Thanks a lot guys !