I run the high end vspec (speed) and I absolutely love it. Its easy to tune, holds a tune like no other engine I have owned. I know the vspec's have lots of bottom end. I have been told the +4 is missing some in the bottom end. I have seen vspecs pull hard at the track. People seem to like their +4's but the review I read in a recent review that did not like the simple design and simple components in the +4 (bearings, crank, carb) Thats just what I read. Bottom line is I would go with the vspec.