I have a GUDE head and it has the racing grind valve job, but they used the stock springs and retainers. Gude recommends that I keep stock springs and retainers and do not go with oversized valves because the valves will kill bottom end power. They said the oversized valves will help top end a bit, but ill have to compensate my bottom end. I was also told the titanium springs and retainers were a lot stiffer and i wish i remember what else they told me, but they mentioned something about the friction in these hindering performance. I know all the GSR guys rev their engines to 9k's but my engine wont be reving past say 7k. Any thoughts, idea's, or theories behind this would be greatly appreciated. My motor is built turbo by the way, and yes im posting this in the FI forum but i wanted to put it in the prelude section as well, thanks guys