Ashley Cobb, the sx8 has a few updates on it to suit american style tracks more. The 2 things that make the biggest difference over the original nrb3 is the 16mm big bore shocks and the new chassis. Those items are inexpensive and make a big difference to even the average racer.
Nixon, great birthday gift! You will enjoy the build, it goes together very well. Use Tonys setup sheet on
http://www.tqracing.net/ as a starting point. Lots of info on this thread to help you tune it to your liking.