I have recently purchased a used pro design cool head. I replaced the stock head w/ the cool head and installed 20cc domes, I started it up, and drove down the road and back about 1 mile and pulled it into the shop, i had replaced the plugs with new ones when i put on the head, well when i took out the plug to check jetting, the plug was still bright white and the tip of the plug was starting to blister. I orginally thought that it was the octane of fuel i was using, i was running 87 in it before the change over and i was going to get some 91 to run in it, anyways, i thought i would check the compression and it was only 100psi, then i thought that i would warm it up to see if it would seal up better, but when i ran it down the road again and came back the plug was really dark and the compression was still 100psi, and all i did was move it in and out of the shop, I know i was a little rich before i swapped heads and i was going to change the jetting but now i don't know what to do. I am at 3200ft and i have 20cc domes, i think the compression is suppose to be around 147psi. When i was running it around it ran perfect. It had great throttle response and it had ran better than it ever has. I can't imagine it is time for a rebuild. What does anyone else think.