[techie610]

From what I have done and seen, and from what everyone else has said, the 4 valve head is about useless. The results you get out of it do not justify the price alone, not to mention the aggravation of installing it.
The numbers of the cams are a sort of name really. I have seen some cams with numbers punched into it about the Lift and Length of that the lobes produce. For an accurate number, you would have to measure with a Caliper and do the math yourself.
However, I do know that everyone I have seen upgrade cams, have put out a noticeable difference in performance.
My father put an A14 on his and it gained about 15mph, lowering the RPMs by about 1k.
For the best performance output versus price/work, in my opinion, is the Torque Spring.

Back to the subject, on a stock engine set(minus Varo weights) an A12 cam does a pretty decent job for the GY6 150.