Rcpete,
If you ordered the mount for your Ram 500 you should end up with basically zero - zero. Alum bracket will be raised slightly at the rear.
For the larger turbines the alum brackets end up flush with the top of the wing, which translates to considerable down thrust. I believe the only reason for the down thrust angle for the bigger turbines is too provide a little more margin for the heat blast created by the larger turbines. A margin to prevent frying the stabilizer. If you have the correct mount for your motor all will be OK.
Actually if your turbine is the Ram 500 you need not worry either way, down thrust or Zero the Bob Cat is going to be fine. Good luck with your first flights, your going to love your Bob Cat-----everyone who flies one really gets hooked ------ me included.
Lee H. DeMary
AMA 36099