Damn glad I showed up here,lets set some things straight.The F15 has a PJS reed engine based on a Kawi piston port 550, the cases ,cylinders,head,exhaust,intake was all PJS .The parts that interchange between the Kawi and the PJS engine are the crankshafts,stators,starters,pistons and rings.The PJS engines did use Wiseco pistons with boost holes ,nothing really special about them other than that,its just a 550 reed motor piston.The stock PJS engine was rated at 70 hp.Now as the to PJS hull being heavy ,thats BS,just the opposite actually,this was the first production lightweight hull,nothing really special about the structure,its S-GLASS EPOXY,no problems repairing it. I have done a few repairs on them,epoxy resin works fine.It was not designed for freestyle,it was a race boat that ran 52mph out of the box.I will be converting one for freestyle in the near future.The bulkheads were weak on the the 92 model boats ,that was fixed in 93 along with several other hull issues.I am glad to know we have so many PJS experts in here,seriously if you don't know just say so,we won't hold it against you!