I have one of the initial Pypes X pipe systems with their muffler on my HO that Scott Tieman always races. It was running consistent 12.60's @ 111 this fall on a slippery Stanton track at the PS race.
Lloyd is correct, it sounds AWFUL!!!! I simply
hate
the sound. It is like a wounded 2bbl car huffing out of a to small single exhaust. Not a prefered sound.
Pypes must have changed the muffler since the original run though. We have the same basic set up on a 350 HO bird and on my '70 RA IV T/A. They both sound like one would expect a Pontiac to sound.
We have not been able to get Pypes to give us a straight answer on this yet.
Mark