Pro M Question

Hey guys

Just wondering if a Pro M Bullet Meter mounted not straight up would make a difference. Due to having a powerpipe the meter needs to be clocked to the 9 o'clock position. Just wondering because my C&L clocked that way seems to have problems on ocasion. Also does anyone know anything about the Universal Pro Meter? They look like they can be mounted any way due to the full circumferance reading. Also which Universal one would I buy for my 1993 mUstang, ther is a bunch of different sizes measured in inches. Also I have been told to order it calibrated for naturally aspirated, what do you all think.

Thanks Guys