Hi mate,
If i was you i would stay away from the losi's, i have had nothing but trouble. But some people say there fine.
I run the Novak GTB System, with a 5.5r in my BMAX. Go for this system or either an LRP, also with a 5.5.
Novak System:
http://www.m-k-racing.com/product_in...7&%3CosCsid%3E
Currently not in stock, but marc can get them very quickly.
LRP System:
http://www.m-k-racing.com/product_in...5&%3CosCsid%3E
http://www.m-k-racing.com/product_in...8&%3CosCsid%3E
Also check your gearing when running these, check my setups in this thread as it is listed on there.
Hope this helps,
Ryan