i have the same cp piston.matzac porting did the port work.suprizingly the stock ports on the zuk heads are done VERY well from the factory.(see what happens as the molds and tooling wear)so he just cleaned them up a bit.he did a little more work to the exhaust side than the intake.did some work inside the dome as well.whatever they did works.mine was the first ltr head they ever done and was shocked at how well it was from the factory compared to yammi and honda.even with the high comp piston it still revs out nicely.if you got the piston off the guy on ebay it is his brother that did the porting.