The piston is not cut, no. The .67 liner has.. hmm, I should learn the terminology for all the ports.. the same 5 ports as the .65 liner, but the three opposite the exhaust are milled on the exterior of the liner for more area whereas the .65 are not, and if the two on the outside of those are boost ports, the boost ports are milled to angle upwards but not on the .65. Then there are two extra ports below all these. Should have taken a picture. But I've seen it written that the .67 has about 10% more top end, I presume that is expressed in hp. We'll see.