I put in a stock LS6 pump when I did my cam and gained about 5psi all across the board. I get about 60 on the gauge while driving and about 40 hot idling. The LS6 pump is plenty for 99% of builds IMO.

 

I've never used a feeler gauge when installing the oil pump because I didn't know u were supposed to but now I'm curious if anyone has better luck using one. Also what's the best way to clean one of these pumps out I had a bearing go on a motor that had 500 miles on it machinist screwed me. So all my brand new parts had to come off to have it fixed and I'm wondering how to clean the pump out good I seen lots of metal on the pickup screen I'm worried I won't get it and it will be in my new short block

 

Pull the front cover off and the hex plug. Pull the gears out, the spring, and the check valve. Be sure to pay attention to how the gears come out, I think there is a front side and back side. You're going to want to look for any scoring in the pump housing if you had a lot of metal go through the engine.

After that, clean everything out. I usually use a parts washer and solvent, but acetone or brake cleaner works fine too. Blow it all out with air if you can.

I bolt the pump on the block before I reassemble, leaving the bolts loose, and use the feeler gauges to center it like the picture below. I'll snug down the bolts one at a time and pull on the feeler gauges to make sure they aren't binding. Adjust the pump until the feeler gauges all come out freely with the bolts tightened.

 

Yep, that's the ticket. I think I must have read the ****-retentive guide to this because I ended up using 6 gauges. Bought Harbor Freight out of feeler gauge sets and now have 6 that are missing just one piece. Still only about $25 total. I acquired what I *thought* was the complete Kent-Moore LS engine tool set and was surprised something for this wasn't included.