Not true about bigger is always better, unless it's a proper thought out solution. As Aebous points out interference is the first problem. and frankly there's not a lot of space left around mine even on 18's. Next issues start to come with brake balance where you can end up with too much ont he front and nothing ont he rear. After that you can have issues with the size of piston. Simply put the master cylinder has to be in the correct ratio to the slaves else it will all go wrong in terms of travel or pad pressure.
Reason the E46 works is frankly it's off the same suspension system that the Zed uses.
