seriously op asks best pipes there so much variations to that question obviously i would take cpi's over fmf's but best pipes for what the money woods moto x dunes. All im saying is after 15 years drag racing banshees ive seen so many big bore big carbed with all kinds of porting and different piped shees and in the end unless you have two identically modded shees both set up by somebody that knows wtf hes doing then try different pipes you might see some small differences. But with all the ways you can f up and slow a heavily modded shee down trust me ive seen many lol just with jetting alone. So when someone says best pipes im gonna answer my way for the money fmf fattys are great pipes! If the op said on a 90 hp shee racing for 5 grand i would have other pipe suggestions