On our level one kit you can run completely stock if you wish but you will see some increased hp gains with an exhaust system. With our level 2 640 kit an exhaust is seriously recommended due to the extra flow and heat. Some good tires might be a good idea to get the extra power to the ground where you want it.
Other than that there is not much else you need to do besides hold on.
If you have any specific questions regarding any of our kits please let me know.