I just had the rss xpipe installed on 2011 gt3. Impressive sound particularly in 2nd and 3rd. Looks great in black and fact you can't see that ugly third muffler/resonator sticking out under rear bumper. When you back off gas you get a cool burble that (shame on me) sounds like my redneck neighbors saleen mustang. Not that this is a bad thing. Sure sounds more complicated and powerful than your typical flat six.

 

excellent choice.

 

cool, very tempting...

how is it at highway cruising speeds and at or around idle? Any significant extra resonance or droning?

 

the sound while at highway speeds is just slightly louder than stock. It is a little deeper and boy does it scream under full acceleration. Very tame when not on it. When sport is off sounds pretty much like stock. No added resonance. Check out guys thread on install of xpipe on his gt3rs with pictures. He must be an audio guy as his description of sound, although I did not follow all of it, seems to be a good summary.