Bike?
Many of the Superbikes already have a 525 - Did you mean 520? If you're gonna change sprocket pitch then yes, you'll need both sprockets and a chain. Probably wanna go up 3 or 4 in the rear with a quick change adapter while you're at it.
Call
www.whitebuffaloracing.com and talk to Mike. I think my switcharoo was right at $300 for an ERV3 and Afam setup.
Sorry if this isn't the info you were looking for. I'm just going by the limited amount in your question.