Hey Beavertim, sounds like a nice boat. Im not to hip on turbos but I would think 5000 rpm would be plenty for a turbo motor because they make soo much torque in the lower RPM. If im not mistaken alot of turbo guys will run AA impellers bucause the motors produce enough torque at low RPM to do that with less HP. There are quite a few turbo guys around here that should be able to help you. A couple months ago in hot rod there was a Merc wagon (around a 59) that had a twin turbo 460 built w/ junkyard stuff (turbos, intercooler etc...) that made like 350 hp and 780 pounds of torque. now thats impressive to say the least. What kind of turbo setup is it?