Yea, porting would be much cheaper. For a Cheetah, you're looking at anywhere from $1,500 to $4,000, depending on what size you want to go. And that's for just the parts, and you doing the labor.
A Cheetah PV is made by the same company that makes the Cheetah Cub. CP Industries. It's a power valved motor. The power valves change your exhaust port timing, depending on your RPM. It comes pretty much drag ported, but with the exhaust port timing being changed, you have a ton of low end power. The power band is almost just like a 4-stroke, and very smooth, but you get the power and scream of a drag ported 2-stroke. Same motor that I just put in my bike. Mine's a 10mil 535cc Cheetah PV. And yes, I ride aggressive trails. I might take it to the drag strip, just to play around with the rice burners a little. :biggrin: