On my previous ride, a 302ci Clev ZA Fairlane, I had a twin 2.25" system (in ACMS) by Lukey, even the extractors were Lukey. I had both mufflers rust out on me at the same time, so that was nice. Anyway, I replaced them with the same Lukey mufflers and didnt feel any noticable increase in torque from rusted Lukey mufflers to shiny new Lukey mufflers. So, next tax return time, I decided to redo my exhaust and a few other things, Didnt like what the lukeys where doing for me so I wanted to change. Its at this point that I must point out that I live 2 minutes drive from Gonzo's Racing Pipes, so I cruised on down there, asked about a similar system they hooked me up with an inhouse no name brand set up and ended up with a 29Hp increase and a 47Nm torque increase with the new exhaust and down-graded cam. So in regards to the last post, yes, this is a 100 good answers question

Go the Gonzo