You should've went with the 1521/1.5Y for the 8S set up. The 1521/1Y I have in my BPP truggy on 6S is insane and I mainly use 5S2P with it now. I use the 1515/2Y in my Mugen MBX5T with 8S and it's faster then any nitro truggy out there and it's only eared for 34-36mph.