The camber adjustment is pretty much at the limit as standard. Lowering anything more than an 25mm, especially with larger alloys is going to be beyond the capabilities of the rear standard camber adjustment (and the fronts if you fit springs or your coilovers don't adjust for camber). Lower more than about 35mm and you will be beyond the capabilities of the standard toe adjustment.
A quick look at the angle of the wheels from behind someone's car who hasn't sorted the camber will soon verify this. You don't HAVE to sort it, but if you don't, you'll be running on about a third of the tread and be getting through tyres every few months...