Unless you are an experienced tuner I think you'll continue to struggle with this combo until you get it on a dyno. Once you know how much timing it likes, where peak power is, peak torque, AFR, etc. it will end all the guessing and make it much easier to troubleshoot and seperate any problems in the rigging vs. the engine. Once you have ruled out all the variables you can call Brett or Brad at BBlades and get them to help with the slip numbers. As far as drives and RPM, I have run bravos and alphas @ 6500 to 7000rpm for years without problems. Low RPM and big torque is much harder on a drive. Ask anyone who builds or repairs drives.. Good luck.

With 2 foot chop on the lake today I was able to get 64 out of her! Thats with a Mirage 21 thats pretty beat up. I'm guessing that a 21 plus in perfect shape would be good for another 2 mph. My boat has a huge hook, I'd be willing to bet that removing that would be good for another 2-3 mph. This boat runs really flat and its very hard to carry the bow up much. So with those mods it would put me right with 242's with an hp 500 which run 69-70 mph.