Made a custom header for a G38..Used as Mac's Products quiet pipe, picked up 800+ rpm with no other changes..Also used a Mac's pipe on a G62 and a Red Max 42cc..They worked very well on both..Most pilots don't want a pipe hanging out the side of the plane...I expect if the ports were optimized for the pipes they would work even better....The quiet pipe was just that...Not loud at all...Easy to do..I made a bracket for the rear of the pipe to hold it on the fuselage...