Depends on what you're looking for performance wise. If you want low end acceleration then look at the Ofna 0630 or the 053. If top end is what you need, then look at the Ofna 086. If you're looking for something different sound wise, take a look at the new pipes that Fantom Racing just came out with for .21 size engines. Since they are made form steel instead of aluminum, they resonate differently.