I'm betting that he needs a shorter set of slicks to get the MPH back up. Common problem, especially when you can't get any wider tires to fit on your car (you compensate by running a taller tire to reduce wheel spin). I had the same problem on my old '70 vette that trapped low for it's ET. Went to a shorter slick (26" vs. 28") and went quicker by two tenths and faster by 4-5 MPH because I could both hook up AND still had the closer to optimal final gearing with the shorter tires. Simple.

http://www.bnmotorsports.com "And I will strike down upon thee with great vengeance and furious anger those who attempt to poison and destroy my CEG brothers. And you will know I am the Moderator when I lay my vengeance upon you."