As soon as I read this, then read Carnivalride's I can see there needs a little clarification. If this a real honest to God APBA, side by side, 120mph on the straights, 80 thru the corners, K boat, you are just kidding yourself with a flat tappet. You will never make enough HP. If on the other hand, if this a blown flat bottom, river racer "k" boat, and I suspect it is, you will probably make more HP than you can deal with by using THE RIGHT flat tappet. Chances are the thing won't be floored for more than 10-12 seconds at a time, on perfect water. I can count on 2 hands the number of people that can drive those things enough to need that HP. I get beat up all the time for saying the terms K and GN get thrown around to loosely by river racers. My recommendation is, follow what Steelcomp said, run good oil like BradPenn, or a good syn, and keep clean underware available in the boat at all times.