When I raced buggies,20 years ago mind but I doubt anything has changed,if I raced a long track indoors on carpet or astroturf I'd put on a big pinion,say between 16 to 19 teeth for more speed and less wheelspin.

If I raced a short track or off road circuit I'd use a small pinion,anywhere between 12 to 16 teeth to give me more "sprinting"ability out of and between corners.Plus if I needed to break traction i.e make it wheelspin to slide into and through a corner or flick the backend out,I could do it easily with a small pinion fitted that would allow the motor to "get on the pipe"quickly.

So like the man says:

Big pinion=Slow acceleration and high top speed.

Small pinion=Quick acceleration,lower top speed but more "driveability",i.e the ability to crawl away and move at a "scale" speed,just what you really need in a Tiger1.

Oh yeh,I used 48DP gears both on the motor pinion and the gearbox spur gear.Believe me,32dp,48dp and 64dp certainly won't mix and match.You wont get them to mesh at all.
I'd say HL 'boxes are around a 32 diametric pitch(DP).Finer pitch gears(48 or 64DP) are more expensive to produce and harder to mesh in a busy production environment.
Miggers