I have a magazine somewhere around here with a documented dynoed power loss under stock by installing a pacesetter exhaust. I can try and dig it up for specifics.

You should have bought my wheels instead, they would have made your car faster :fawk: h: actually, they might have.

But to answer your q, the heat shields aren't really necessary, they just keep the bottom of the car from heating up. I ripped mine out because they rattled (that and my muffler fell off :exnbp: ), and I haven't noticed any difference at all.