Originally Posted by forza370z

OP, this is a good thread and I hope people here be honest and tell the truth.

Before I got everything on my g35 coupe 2 years ago, I did whole lot of researches on the forums. People on the internet were singing of how awesome the F.I. exhaust sound like yet not to be too loud, how hard it pulls, how much hp gained... I was super excited to order mine. After I installed FI HFC and FI carbon fiber exhaust here is what I can say. It sounds really awesome no doubt. It's loud(not qieut like some people declared but I liked it). It looks great too especially the carbon fiber canister. Top notch quality hands down. As far as the performance gain from my butt dyno, it's definitely different from the stock. I lose low end but gain at high end. The annoying part is at 2-4k rpm when the exhaust starts to get really loud the car doesn't go faster. This was my only complaint. When I switched back to stock the car felt much faster and responding. But the FI exhaust kickes in after 5k rpm while the stock gets sluggish.

So if you ask me about the performence gain, I am not very impressed(as almost all aftermarket exhausts on NA cars). You might feel power lose at normal driving. F.I. declared 20 wheel hp gain and that might be true after a fine tune. But will it make day and night different? Don't get too excited. Think about this way, the Nismo declared 18 hp gain over the stock. But if you check the entire forum, how many people actually saying the Nismo outperform the stock. Bottom line is it's a sick exhaust but not really makes much differences on performence gain.