Brushless RC8T gearing?

[Ryu James]

so i am building a RC8T and converting it brushless. i have notice that the spur gear on the T is a lot larger than the buggy spur gear. why is this? i have a losi 8 and 8t that are both brushless and both came with 13/48 gearing. i think the RC8T spur is like 54t. i am wondering since i am converting to brushless if i could goto like a 17/50 or a 13/46 setup and be ok for temps? i have 15/48 in my 8t and it screams but temps are great. i dont know what the front and rear gear ratio is in the RC8T though so can anyone recommend the best gearing.
this will be setup with a Tekno Neu 1515 1.5D 2700kv and 5s
i like to go fast.