Some thoughts ...
- more front/rear wing
- increase gap to the ground (avoid aquaplaning)
- less powerlocking
- adjust brakes more to the front
- less preload
- make your car soft to avoid aquaplaning
I wouldn't make the gears bigger, shift earlier while accelerating! Barcelone has quite a lot of turns you take in gear 2, just brake into a turn with gear 2 and directly after your braking process shift to gear 3.
Hope it helps.