I've autocrossed my Chall T/A since 1975 in the SCCA Solo II events... car is currently nationally prepared to run in class E/Street Prepared (since its class inception ~1986). Although I've always run a mechanical fuel pump, I've never had any fuel starvation problems.. In fact, I've always preferred to run the auto-x events with as little weight as possible... typically starting the event's day with about 1/3 tank of gas... ending up with about 1/8 tank... tank is factory stock. One note -- if you run a Challenger with more than 1/2 tank of gas, or worse with a full tank, you'll not only have all that extra weight (bad!) but the fuel will probably spill out of the side-filler onto the quarter panels unless you have a very good sealing gas cap, and perhaps wrapped with small cloth soak to it up.... The g-force in such events can be pretty high to force the fuel up the filler and beyond the gas cap... from my experience!