I just put one of these together with a new OS 50 SX and used the stock muffler. Pretty good combination. The new OS is so quiet you can hardly hear it when it gets away from you just a little. Plane insane, you may have trouble getting 2.5 wheels on it. the largest I could get on it was 2.25 due to the small wheel pants. You have to put larger wheels on it because the ones that come with it scrape the asphalt.

This is my 1st Kyosho and I think they are overpriced for what you get although it flis well. Almost wish I would have bought the GP Extra 300 in the same size catagory.

Dave