I have a DA 50 in my Patty - Maiden flight today, I put a ZDZ 50 in the Hangar 9 80" CAP and it will turn a Mejzlic 22-10 at 6700. Dick Hanson has done mucho testing on the ZDZ's and will attest to the fact that the 50 likes the tuned pipe/cannister setups but ZDZ is listening cause the new 50 they are making has less aggressive timing and makes more power on the in cowl muffs. If I buy another 50 it will be the DA or a BME 55 if that ever comes out.