Disappointed in my 383 on the Dyno

So went to get some tuning done and my 383 only laid down 329 hp and 356tq to the wheels on a Dyno jet

Some of us can tell a whole lot about things in what seems like an a**-backwards way.... Please give some specs about the entire car and drivetrain, and try to go to the local drag strip and get a few good time slips, then repost some results here. HTH, Lefty71