Autotech, HPFP, APR in that order. I've had the autotech and have apr now. I would trust hpfpupgrade after reading many positive reviews. I would avoid kmd at all costs. My 1st was autotech, but it was ruined due to finding out, after I got the apr, that my tech had installed the used cam follower along with the new hpfp and so I hadn't planned on checking the cam follower for wear for another 4k miles :( KMD has had too many issues with previous versions that I would avoid which ever version they are on now...even though revo has gotten involved with their quality issues I believe. If I needed another at some point I would get autotech or hpfpupgrade.