It sounds like it may end up being more expensive than the 900rr. If you have your header moddified you would be in uncharted waters and need to have her dyno tuned. Ideally you would do that anyway, but if you go the 900rr header route, their are others here with maps. I don't even run a power commander with my 900rr header, but idk if you would be able to get away with that with a modified stock header.
Don't steal. The government hates competition.