I understand why the piston is in there..thier theory is when properly tuned the pipe will have more consistent backpressure and will never load up.I either can't tune the engine right (never had a problem till this pipe) or the pipe is not what I need like you said.However,I already have it so I'm going to modify it...I don't see how it could get any worse at this point.I tried all the settings and eventually broke the little bending pin that holds it in,I've read the tuning instructions and followed them and have given it quite a chance for a couple months but its time is over.I could get it running great,then 3 minutes later it would be sluggish and close to dying..making my head temp really erratic too.After I get the single stinger in I'll seal the 2 halves with some Permatex so it doesn't leak everywhere and mount it and try to get some pics up.