Brake Upgrade
#16
Where are you getting that info from? The factory front brakes are 350mm or 13.78" the rears are 348mm or 13.70" If the 150's came with 15" front brakes from the factory, the smallest factory wheel you could fit would be a 20", and we all know that the base wheel diameter is 17".
#17
Having more Pistons for braking is what makes all the difference. You may need to change the brake master cylinder and booster due to the added volume of brake fluid displacement. Having a floating caliper has its pros and cons. I know first hand having had a sports car people were warping rotors left and right. Less tolerance compared to having a floating caliper. Changing the composition of pad and rotor does not necessarily increase brake performance, adding mechanical braking power does.
Be advised that drastic changes to your wheels and brake system will change the performance of your safety systems too!
#18