[Mitch Leland]

Originally Posted by FPB111

The XLF option is the Porsche Sport Exhaust (PSE). Two stage with vacuum controlled valves to allow it to pass noise tests. The valves are controlled by a switch on the dash and with a computer override to close the valves at certain RPMs to allow it to pass european noise tests. Many disable the valves to always "open" which is the same as the stage one mod. If you want a little more bass do the "Orange" cap mod on your intake.
Anyone got a spare Orange Cap tey can send to UK? - Rennlist Discussion Forums

http://www.renntech.org/forums/topic/6422-intake-air-box-modification/page__hl__orange+cap

Orange Cap mod - Page 2 - Rennlist Discussion Forums

Are you saying that even if the switch is off (open exhaust) it will automatically close at high RPM'S? If so I was unaware of that...

Thanks,