I currently have both Vspec in Losi 8 and GRP in SX8. Vspec is a piece of cake to tune with about 8 min run times running 220. GRP is all about low speed on flame outs but getting 11 1/2 min run times at 205. I can not complain about either engine but the run time on the Grp is a big advantage. I would say either will get the job done but the GRP will give you less pit stops in the main. The gentleman with 10 min on a Vspec please give up your secret LOL