My advice if you're thinking of lowering your car is to always go lower than you originally intended. More often than not, when people lower their cars they say " I wish it was a little lower ", it's happened to me on my past 2 BMW's. It just cost me more money to get the second set of springs and the right stance. Btw, don't install shorter springs without installing proper dampers at the same time.
Accordio, you have any soundclips of your exhaust handy?