i'm going between two brake set ups for my car and would like some input!

The 850i in the front and 540i in the rear
(+ of this set up: Can use my snow tires/wheels, way cheaper!)
or

Going all out and buying the wilwood kit from UUC
can be found here: http://www.uucmotorwerks.com/
(+of this set up: HUGE braking power)

Now, are they really worth that much?! and will they even fit under my 17in wheels?