I've tried dropping to 6.5 from my normal 7.5-8.0 and it felt squirmy at the top end letting off; didn't improve 60' or ET so I went back to 7.5-8.0. Your deal may well be different; my car's a 3000-lb low-10s footbrake 368CI SB/904 Duster running 13x31 Goodyears on 15x12 Flys. I've run up to 10PSI but it leaves & ETs better (6000 stall) @ 7.5-8.0.
