Mainly the C40, it's cheaper then the c50 setup and will give you good performance. Great(balistic) performance is with the c50 6.7:1 17x10 and 6c packs. THose are rockets. If you read through the post, I know there are alot of them which is good for info, there is just about every motor combo out there on it. I switch between the cem and hacker. just to play with it.