All depends on what kind of kit you get, Your front brakes do the majority of the work. Most track cars only upgrade the fronts, not worth spending the extra money for the rear.

Also If you get a properly designed system like Stoptech, they are engineered to work with your stock rear brake system.

 

To answer the original question, no, not at all. You can argue that a $2000 brake upgrade has more functional benefit than $4000 for rims. More people will notice the rims, but depends on where your priority is.

I haven't seen anyone on this site with STi front calipers on their G35. 95% sure they won't fit without a caliper bracket. I heard that the rears may fit, but the Sti rear caliper has 36mm pistons as opposed to the G35/350z 40mm.

The only custom brake setups (not off the shelf ones) on non race team cars were a 6 piston Porsche Brembo setup on a G35 in Taiwan, the 15.2" rotor kit with a relocation bracket for stock Brembos, and my 13.6" setup with a custom caliper bracket.

 

Other than lookin cool adding Brembos won't make a large diffrence. I
wouldn't even consider it an upgrade. Adding an AP brake system would
be an upgrade but is it really worth the $ to be "that" cool? Find yourself
a set of Volk 19s that you really like.........that's an upgrade!!

 

Hell yeah if you have the money go for it.

I had a Stoptech 14" BBK on all four corners and it was BY FAR my favorite mod besides my rims.

 

I just upgraded from my 05 brakes to the oem brembo and I can not tell the difference in stopping power. The brembo at this pt is more for looks and is not really an upgrade in my case. The front 05 non brembo rotors are the same size as the brembo rotors.

 

i have an 03 non brembo coupe, someone is selling me their used brembo calipers, rotors and pads off an 04 coupe. My question is do i need to change the brake lines on my 03 for it to work?