I agree with Silversurfer. I used to run a mejzlik 23*8 on pitts muffler at 6400 rpm. Not bad for IMAC but after using a Bolly 23*8 wood I beleive the weight of the mejlik was a bit heavy for the engine trying to throttle up (especially for 3d). The bolly wood 23*8 used to get 6600 on a pitts muffler. I have just changed to a canister and a 22*8 Bolly wood and get 6900rpm. Throttle response is excellent especially for 3d and in the long uplines the recovery from snaps,ect is quicker. These figures are all at sealevel.