Keep the Alpina wheels (I wish I could). They are part of what an Alpina is. As far as lowering it, I'd advise not to. The suspension is really set to handle as is. Unless you are tracking the car and driving near it's limits (which most people don't) there is no advantage other then personal preference. Either way, you have a very cool B7.
2012 Alpina B7 Silver
2010 Roush Mustang (627 RWHP)
1965 Vette (ZZ502)
2005 Ford Racing Mustang in SCCA T-2
SCCA National Driver