OK, I went back through my notes. Ram 1500 with supercharger, Sport intake/exhaust, race suspension, and a set of used Rallye wheels from one of the winged cars. 490 hp, S2 (stock sports) tires. Margins of victory (MOV) at the three races:
Fuji: +4.980" over the Silverado SS
Laguna: +5.514" over the Silverado SS
Seattle: +7.778" over the Silverado SS
I'm sure I could have done it without the Sports breathing kit; I tried that first and just left it on when I added the blower. I probably could have done it without the suspension upgrades, too; I only put that on because I wanted to see how the truck look slammed like a race truck, but it didn't go down that far. I ran this race early on, when I was only 3% or 4% done at the most.
Actually, the Ram was fun to drive, particularly at Laguna. I had a blast.