Yeah, they could be counterfeiting them. I saw were the Dynojet Jet Kits were being counterfeited. Check out this link.They are not available unitl 4/15/10 from Hot Cams. Use cation when buying one off of ebay. I find it wierd that ebay has them available before Hot Cams.
Do not go above a stage 2. The stage 1 will give you noticeable power gains over the entire RPM range, made to use stock exhaust/intake. Stage 2 leaves the bottom end about the same but will stretch your arms above 5000 rpm. That is made for a quad with minor modifications such as pipe and air filter. Stage 3 is for a completely built motor.