Greg can tell you which pumps he's running but one is larger than the other. The big pump put out so much volume, that with a -6 return line, we couldn't open the regulator enough to get it down to factory pressure.
Just went to his thread and looked. The 525 pump is way too much pump for the factory lines, the 450 may or may not work but I'd be suspect
If it's a stock tank setup, I'd be looking at an aeromotive 340. I'm using two of em myself.