How high of an RPM can stock springs handle? I have stock heads that have been port matched, with 1.7 rockers and an E-cam. Given that the power band is higher up in RPMs, I wonder how high the stock springs can go? I haven't figured out if I am going to go with new heads, or just leave the engine the way it is. If I leave it alone, then I might want to look into replacing the springs so I don't have issues at higher RPMs.