Thanks guys,
That GT500 was probably closer to 4,000 lbs with those 20" wheels. They're 3850 or 3920 depending on the options (stereo setup, etc).
I think he was making ~640 on the street dyno that night - considering how Brad and Thrust seemed to be pretty even with Thrust's ~605 RWHP and the '03/'04 weighs 3665 lbs. That's a pretty significant difference in weight - takes a lot of HP to still hang with that ~335 lbs extra.
Tim does tune so the ECU starts pulling timing a bit sooner than a lot of other tuners, I believe it's 130* F for Tim and usually 150* for most others, including mine.
I think Brad weighed in at 3110 on the scale at Reynolds - the catted X-pipe and headers saved some weight - forget what fuel load that was with.