Go with Patto's suggestion.
The older cars ran fairly tall gearing std out the box.
To help as well you could go to a smaller brake pulley to shorten the internal transmission ratio.
casterracing EX-1 Pro, SP Silver Arrow
TOP Racing Scythe, SP 17.5, SP GT Pro 2.0
TOP Racing Scythe, SP 4.5 V2, Hobbywing Xerun 120SD 2.0
TOP Racing Scythe, SP 13.5, Hobbywing Xerun 120SD 2.0