I have a Shrike with a OS .46 FX with a pipe. I ran it last season with the stock muffler to break in the engine and I thought it was fast then. This year I put the pipe on, WOW what a difference
! I have not clocked it yet but it's fast. The only modifications I have made have been, I replaced the rudders with 1/8 sheet wood instead of the build up type. I was getting some flutter with the stock rudders.
I get an interesting whistle when I fly. Does anyone else have a Shrike that is whistling?