I am the proud owner of 2 300 kits used on my racebike. I only have good things to say about the kit regarding my setup. Matt and I have worked on some small modifications to the kit in the past. I use Wiseco unmodified pistons. One warning which may be obvious, if the pistons get too hot on top, they can deform just slightly to pinch the ring, and thus lost compression from no ring tension, but no damage to the cylinders at all. In fact, if I could get the ring out, the groove could be modded and the piston reused. Otherwise, when jetted properly using the fuel and setup I have, I have wonderful results.
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I'd rather be racing on my Harc Pro 1998 NSR250SP that is really tricked out!!!