I have the RSR and it sounds amazing at idle. It is loud, but not unbearable under normal driving. Open up the throttle and it's crazy, crazy loud I drive with the silencer in a lot =\ It's also the straightest and probably the lightest exhaust for the MKIII so it should make the most power, even though it's probably less than 1hp of difference.
Even if it is discontinued there are probably plenty still in stock in warehouses. I can't see any MKIII exhaust selling like hot fire and usually there's a minimum order so most places that had it in stock before the very recent discontinuation will probably have a few left.
Even if it is discontinued there are probably plenty still in stock in warehouses. I can't see any MKIII exhaust selling like hot fire and usually there's a minimum order so most places that had it in stock before the very recent discontinuation will probably have a few left.