Hey scotty if you do a really good port and polish job on it then you will see huge jump. Did it to two different (well me and my buddy did) traxxas .15 pro's and the second one ran stronger than their 2.5 race engine did. Wont say it made it past 2 and half gallons though lol.

I dont think about rebuilding it till I notice a huge loss in performance. But if you want to take it to where it NEEDS rebuilt then you will do it when SugaFree said to