I was wondering if anyone knows if there's a difference between Brembo's on 03's vs 04's. My car is an 04 and I happen to notice another bolt sticking out btw the wheel bolts (highlighted in red on the second picture).

You'll notice the first picture with the blue pads doesn't have the bolt i'm referring to.

that is the bolt that keeps wheel/tire techs from sticking the rears on the front. most guys need to remove it before putting on aftermarket wheels.

^+1

Okay, that's great. I bought a set of winters and I was afraid I wouldn't be able to use them because of this bolt.

Is it easy to remove? Just remove it?

Yep, just remove it. Very easy.

remove it? how?

yea how would u remove it. so 100% sure, its only for that reason stated above that its there.
i always thought it was to held the hub together. no wonder why when i tried on a set of 20s off another g35 it wouldnt fit. that bolt was in da way.

The bolt is there strictly to stop the rear wheels from being mounted on the front. Take it off with a 12mm socket or wrench... takes about 3 seconds.
-GP-

Yup, removes with the use of a wrench...what a coincidence, I was just about to post the same thing