When I talked to Mike at Cascade he said they had dyno'd a 421 cub at 101hp to the back wheel. The cylinders he said were right out of the box, not even cleaned up. I don't know any other detail on the set-up other than it was on pump gas. This guy is adiment about not doing any extensive porting on these cylinders at all or you kill the reliability of them. Talk to Jeff at F.A.S.T if you go with the cubs, his turn around was 1 week with a clean up port if he has them in stock, and he does the clean up orting for free, you just flat out can't beat that. From the looks of the cubs compared to the stock cylinders, there is absolutely no way to match the porting on the cubs, the ports are just flat out massive. The ports are the same size as the big cheetah except the intake. That's why the cubs are performing as well if not better than the big cheetahs cause of the transfer port size is not acting like a bottle neck for the bigger bore. Take nikasil plating, larger water jackets and out of the box porting and you have one hell of a system that should be way more reliable and make more horspower than any stock ported jug. Anyway just trying to help with your decisions and what to look at, I was in your boat just about a month ago. The decision was easy once I layed it all out. I'm sure you wil find out the same thing.