Asa far as your eigne. alot depens on your price range. but im guessing your not wanting to get a $300 race egnine. I would definely reccmoend the Novarossi T21bF. Its got crazy bottom end torque., not as much RPm as engine slike the S7, but it makes up for it in torque. On a small track i would put up against any high-end race engine. A good pipe for it is the JP-2. The price is also great its around $180. Just so you know the T21Bf, r21B, and N21b are the same tying