hello, can anyone tell me the difference between the two. does the speed control of the 13.5 ss make that system faster than xbr sport system. if you were to put sintered rotor in xbr motor would it be as fast , xbr seems to be a little cheaper system even with theupgrade hope someone can explain the difference thanks!http://www.hobbytalk.com/bbs1/images/icons/icon10.gif

The 13.5 included with the XBR is the older non sintered version it might have smaller bearings too. If the 13.5 has smaller bearings, you can only install the sintered rotor with the over size bearing kit.
I ran the older version 13.5 all last year with no problems in 2wd Off-road. The 13.5ss is supposed to have more torque but I ran against many with no problems.

My Son is running the XBR with the 10.5 in 2wd mod class and it works flawless
I would recomend the xbr series just don't forget they are limited to 8.5 motors.

If you are purchasing new, your better combo might be the XBR and SS13.5 Pro motor, if you only plan to race 8.5T and above. The price would be @210. You then have a motor with the sintered rotor, which Novak recommends for racing.

The sintered rotors hold up much better in racing environments because they can handle much higher motor temps. We do not recommend the EX motors for racing.

We continue to make the EX (bonded) motors available because certain tracks still require the bonded rotors in stock racing events. We have never offered XBR/SS Pro systems. So many systems, so little time..... ;)