I'm debating on purchasing and installing the ZZP 1.9 modified stock rockers om my 1999 GTP. I have 119,000 miles on it, and have the Plog and 3" downpipe for modifications. Otherwise it is all stock. I still get between 3-5 knock retard at 3rd gear WOT. This is my daughters (17 years old) car primarily and I drive it once and a while. We plan on putting a lof of miles on it and want it to be reliable when she goes to college with it. My question is, how reliable are the 1.9 modified stock rockers? Are they designed to last 50 - 75,000 miles? Anyone have any experience with putting a lot of miles with these? I may in the future put a 3.5" pulley if the KR is all gone.