Can't say if it is under tired or not but I think it is. I see every one else running a 16.5-17x33's and some with 34.5's. I have access to all of the 17x33.5 and 34.5's that I could ever use, but I have no 16" wheels. The car runs really well for what it is. The track that I have been running it at has several dragsters and most there have 565's with BB3 cylinder heads and we run the same et, so I figure that mine is running ok. I understand that the big tire will slow me down, but I ran with a few guy's that ran this same D2070 tire that I have and had 4.72-4.73 time slips like they was ran off of a coping machine. My car only moved .002 from the 330 to the 660 all weekend. Still ran 4.85 to 4.88 and 1.065-1.086.
My converter was not set up for a dragster, was set up for my 2600lbs door car and it is a 8". Any ideas if this is what the problem is.....