Jeremy, 145.1 is my best top speed there, no draft, no wind.
My data on the superkart top speeds is based on my observations from racing with them. Generally, my fast lap pretty is much the same as a 250 twin superkart fast lap. They kill me on the infield, but I have them on topend. A well-tuned (Robby Harper) dual engine kart with two 125’s pretty much runs the same laptime, also with 145 top speed.
Johnny West has very good data on superkart speeds, laptimes, etc. from Daytona.