I have a Skip White 427. 560T/560HP. It's on a 15' hull. 2:1 belt drive. Three blade whisper tip 2.0. I turn it at 5000 RPM's.It definitely goes where my 350 wouldn't. I have about 20-30 hrs. on it so far. My hour meter recently quit working so I don't know the exact hrs. It had a small problem with the valve covers when I received the engine but they shipped me a new set and when I got them I sent the original set back. I had mine built with forged crank, pistons and connecting rods. AFR heads. ARP bolts. In other words I didn't cut corners on anything. I bought the dyno package so the engine came tuned and ready to run. The engine came well packaged and was built, shipped and received earlier than promised. All I can tell you is so far, so good. Only time will tell. They offer a one year warranty on airboat engines. If you have any other questions let me know.