4s vs 5s and gearing

I would like to have harder acceleration. For sure, little more top end would be nice too
My friend have a Jammin CRT truggy with the new OS .28XZ and i want smoke it on the track.

so if i well understand, if i go 5s or 6s, i must to gear it down to stay in the 40mph range, like on 4s setup???
But if i keep the same gearing, i'll pull more curent??