455 Rancher Big Bore Piston and Cylinder

[Chainsaw Pete]

I'm thinking about doing this to my Brand New 455 Rancher I got 2 years ago and I've only run it 3 or 4 times. I like it but it could up a little more power and a ported muffler.

Just curious, what kind of money does it take for the parts, and what kind of hp increase can you expect? Let's figure OEM parts, since that is what was recommended in the original thread.