Interesting...I had a juice with attitude when they first came out for the 305/555 motors, i didn't have a rail pressure gauge, so i can't give numbers then, but I blew one relief valve, and it took out the rail pressure sensor. It could of been a bad box or maybe my truck was picky...I don't know...I got rid of it after a month for the TST, but if it works, it works every truck is so different it may get you the performance your after.