Obviously, I've never worked on a 250 but I would imagine you would definitely have to rejet. Just by punching a couple 1 inch holes in my airbox, I'm up about 4-5 sizes on my mains. Pods would flow a ton more air than my modded airbox. Also - how do the plastic side panels attach on the 250? On the 400, it bolts into the airbox. You'd have to figger somthing out there, too. Good luck!