I've been following this forum for quite some time now and finally got my STi around Christmas. I've been wondering if the exhaust bypass that Quick Time Performance (quicktimeperformance.com) sells would actually help diminsh the backpressure in the exhaust system. In addition, you could switch back from open to close with a switch, restoring your "stock" exhaust flow. However, even if the butterfly valve is closed, wouldn't it still affect the flow of the exhaust system by creating turbulence? Or is the length of the exhaust system after the Y-pipe long enough for the gases to get fully-developed? What do you guys think?