Originally Posted by roy'sz

You could be suffering from a caliper failure where it is slow in response to pressure and the relief of it. Have you thought of Nissan looking into it? Is it only on one side or are both warped? Im not trying to be prude either but comparing sedan brakes to 4piston brakes is like apples and oranges. 99.9% of sedans have floating calipers in comparison to fixed calipers. When you have a fixed caliper the sensation or warped rotors is more evident or apparent then on a floating caliper. The reason you cant feel it as quickly on a floating caliper is the caliper is able to move and not get any binding from the rotor forcing the caliper inwards or outwards (hope this makes sense).

Also since you brag about your time of 13 minutes (which is cool by any means to brag about times) how much time do you have before you park your car? Is it city driving where you don't have 10 minutes of non brake driving to cool the rotors down? If not that could be the most probable cause in the rotors warping. These cars are designed to take a beating, but HEAT is the most common problem in all aspects:brakes, engine, tires etc.

I'm 28 and have owned 2 mustangs, 2 sentras, 2 ford rangers, 1 Toyota Tacoma (big brake kit) and 1 370z. Only 2 have had 4 piston calipers and my experience with brakes is pretty spot on being that I have glazed rotors and warped them myself too many times to count when I was under 22. Take an honest look at your driving characteristics and maybe there could be probable cause there rather than it being mechanical? Also if you google image search the brembo kit on a mustang it is exactly the same style caliper. Just a fyi all 4,6,and 8 piston brake kits are FIXED calipers just like our Z's.

Hope this info helps.