A Huskey 250 engine ain't a nitro engine,they simply drag in too much dirt,the tiniest particles of dirt will eventually kill a nitro engine and K&N's,S&B's and all of the varients are pretty poo when it comes to nitro mills.I have a bank of 4 K&N's on my '81 Kawasaki GPZ 1100 B2 and they're great on what they're designed for,the small ones like whats fitted to nitro's are designed as filters for crankcase breathers and the like,they do look the dogs dangleis (not that i've ever seen Dog's danglies) and I have one myself that came off a Macstar .28 6 port I bought off some one but it never gets used....