Installed this crank kit on my 06 350 Raptor and it was unbelielevable. I raced a stock Suzuki LTZ400 and it wasn't even close. I beat it by about 5 or 6 lengths. If you want a power increase, this crank kit is mandatory. Well worth the extra money.
There's no need to machine the head, but you will be required to run the Hot Rods Big Bore Stroker Piston, because they've designed the wrist pin bearing location 2mm higher to accommodate the extra stroke. Although, you will have to bore the cylinder to accept the 89mm bore piston. Your options are to re-sleeve or bore and re-nickelsil the cylinder.