We have at least one guy at our local track that runs a XBR and a 17.5 in his stock XXX-T MF2... he is always fast and at the top of the race. No fan either..
If you don't already have a 17.5 motor.. you might want to consider the updated Novak Havoc... brand new with a SS 17.5 they run for $149 everywhere.
Jerome
