Let's say that I'm running the Crower 404 stg.3 cams (or the GUDE stg.3 cams, their site says "Valvesprings Required" but nothing about retainers) w/ the Crower dual valvesprings. This is for the B18B1 LS engine.

Are the titanium retainers necessary? I'm just wondering because someone's selling these 2 things, but I can't seem to find anyone selling the retainers. If the stock retainers can with stand these aggressive cams (using stock redline), please let me know.

Much appreciated. TIA