At what point should the stock sea pump be upgraded? I'm around 525-550 hp and when I run my engine at WOT it will heat up to 170-180. I'm using a crossover and have drilled the themostat which helped but I still don't like the temp climbing like it does. Would running a 2 stage pump like the Eickerts help or is it a waste of money?

Stock pumps will feed plenty of water for what you have. I'd look into a cooler t-stat, or no t-stat and see what your water temps are. What oil temp do you see? Do you have water psi gauge?

Another thing could be pieces of old impeller stuck in the oil cooler, or a issue with the supply TO the pump, as in a collapsed hose, etc.

Strange, mine is reverse, I drilled 2 holes in a 160deg therm with the crossover and bypass. Normally runs 150 on plane and 170 idle. Stock pump should flow plenty of water.
Have you checked the water pressure?

This is a higher flow stat this is what i went too and I run right 150 155
http://www.cpperformance.com/p-14347...hermostat.aspx

That might be the ticket! I've been running stock merc themostats without much luck