If you are on a budget the s5 rocks, gets on pipe fast and has a good top end and only costs around 230.00. If you have a little more money to spend I would get a ws7 on the c6, even more power everywhere, maybe too much with a c6. You cant go wrong with an rb, any of the 3 motors mentioned can easily go for 8-10 gallons of fuel if cared for properly.