mach5 had it i think on his sti..

 

oldmansan has it on his WRX.

 

Power gains between these exhaust will be minor unless your pushing 500+ hp. As for sound its got a deep to raspy note as the revs get higher. Not bad though. Ive hurd some non subaru owners comment that my car sounds better (stock exhaust sti) than his (rsr turboback sti). My 2cents

 

about a 40 HP gain proven by trap speeds (4 mph above stock speeds) and the fact that it takes me longer to run down my friends STi in my 3000gt.

 

straight piping, slip joints except where the downpipe bolts up, very nice bellmouth opening on the downpipe, light, and not too loud. I had the Blitz Nur Spec, and it's a good exhaust, but a little heavy for me, has a very large bend before the muffler, and is quite loud. I like the tone of the Blitz a bit better. By the way, Invidia and RSR are not affiliated with each other (used to be).

San

 

the RSR is VERY loud ( i can hear my friend rasing hell over 1/4 mile away) but is mean sounding at WOT.

i dont know what other options you have but i would buy the RSR for the performance.

 

Blitz Nur-Spec is one of the best catbacks out there. That said I didn't like the weight or the big bend before the muffler. The RSR is much straighter and lighter. I was going to go with a titanium catback, but after lifting the RSR, couldn't justify the cost. The RSR is very light. I don't have definitive dyno results, and if sound is an issue, you might want to hear both. Unfortunately, I have equal-length headers that most don't like the sound of. I'll sacrifice the "Suby" sound for performance myself. The WRC car uses equal-length headers, and I think they do because of the exhaust pulses. If it didn't perform better, they wouldn't use it. Lastly, the Blitz is considerably louder than the RSR. I run the RSR without the silencer, where the Blitz without the silencer is too loud for the street in my opinion.

San