Just to put some of this to rest, lets be absolutely clear on what your 400 dollar savings difference is:

What you sacrifice:
1 piece instead of 2 piece rotor - but as rara him/herself pointed out, if you don't need slotting or drilling on a street car, then why do you need a 400 dollar more expensive 2 piece rotor set?

A rotor that is directionally vaned, for just a vaned rotor, but again as rara stated, if the SVT rotor/caliper upgrade is so great the these should still be great performers.

11.8 rotor diameter instead of 12.2 - that's a loss of 3.3% in diameter, however you get a .9 inch thickness instead of .81, that's a 10% gain in thickness.

You do not need an additional spacer set (add another $40) to fit stock wheels

You do not pay shipping

What you gain:
Absurd stopping for a street car, I got light headed in this car when stopping from 80 MPH because it stopped so fast, and our test car has VERY mild tires, lock up at low speeds was a given on 3/4 pedal.

The EXACT same calipers, and your choice of pad compounds.

$400 dollars in your pocket for an exhaust, CAI, STS, headers, better tires, sway bars, TB upgrade.... need I go on?

If your absolutely determined to have the most absurd stopping power in town, then you need to build your own kit with the 14 inch rotors, and use something like the P6R and titanium brackets, but those claipers alone would cost you about 40 grand for the pair

If you want a great looking, great performing kit at 1/3 less cost than the next best option, this is it, I don't want to debate what is or is not needed on a treet car, thats not Rara's descision or mine, in the end it is up to you YOU, the owner and driver of the car to decide how to spend your money, we have been straight forward with the facts from the beginning so here they are (once again) as plainly as I can put them!