the cnc´d version of the 360-1s are often leakers in the exhaust port as far as i know. I did some research because i want to run a set on my car, just bought a new, unmolested set that will be ported at IMM engine. Swap is planned during winter time, so no results at the moment.
So, this parts is interesting to me. It was my impression that the differences are in the intake port shape, and the exhaust ports on -1 and -2 versions are the same.
