We went to anything over 800hp or twin turbo towing trucks because they are very aggressive on cylinder pressure loading and can cause them to leak. Orings and ARP2000 is better than 625+ without the orings for the in between builds if budget is an issue also.This is what I do! Anything 1200hp+ gets o-ringed on the block side and 625s. I've yet to have an issue myself up to the ~1600whp area.