OK. I just got some hard numbers this morning. The 72 with wild cat 10%nitro and 18%oil(80/20 blend) I was getting 10,400 rpm with a Zinger pro 12-6. After opening up the baffles the rpm jumped up about 500 rpm and the idle and midrange were much smother and the high end was just singing. Put the tach to it this morning at the field running Cool Power 30% heli mix which is all synthetic and, acording to their web site, 22% oil low viscosity, I was getting 11,300rpm! Now we're fly'n! Before, I flew around at half throttle, anything less and the plane wouldn't hold altitude well, and WOT was needed to bang it around. Now I can stay in the air at 1/4 throttle , take off and fly aerobatics at 1/2 and go hog wild at WOT and it really cooks now. Thought about up'ing the prop to a 12-7 because the Cap 580 loves it fast and I've got the power now. Thought about the open header deal with the Formost tube and might try it to see if there is any more gain. If there is the 12-6 will then be too small anyway and the 13-6 or 13-8 looks to be the next option. Anyway these are just my own observations any anyone who has "been there, done that" please jump in here. Mike