you don't need a tune for UDP's. All it does is reduce the amount of HP robbed by the accessories. It would be no different than going from a heavy 18" wheel to a light weight 16" wheel. The power your car makes really doesn't change, it's just that you don't have to use as much of the engine's horsepower to turn the accessories... make sense?
Good choice with the Steedas, only way to go. Don't forget to get a harmonic balancer puller, and some black RTV gasket maker for the keyhole slot on the crank.