I've tuned several LS1's with HP and LS1 edit, and this weekend was my first LT1 editing session. With one guys car, everytime we edited the fuel tables, his A/F stayed the same, so we checked his fuel pressure and when he went into WOT he was loosing about 5 psi. Would this be enough to keep his fuel trim so lean (14.0) he made great power for a bolt on lt1(340rwhp) but I'd like to drop his lean condition. Any suggestions?

 

Is it the stock pump?

 

Yep.