RE: Tuning recommendations for a YS .45?
Prop,
just another option - you can get an adapter for the YS to bolt the ultrathrust muffler to it. Runs well with the tuned mufflers. Sometimes that makes for a less invasive installation on some planes.
The 7.5cc pipe is good. Use that as you plan.
Definately ask Dave about the binding. Sounds like something is goofy.