How heavy are the stock rotors? I tried searching with out any luck.

 

brembo or non brembo

 

either way I wouldn't expect them to weigh more than ~30 lbs?

 

A 28mm x 11.08" Q45 rotor weighs less than 20 pounds ~~19lbs...........G35 had various stock rotors depending on year and Brembo.
Fronts usually weigh 40-50% more than rears.

Rotor weight is critical and the heavier the better in most cases, as a 10% increase in weight will lower [spread] the heat rise from braking by 10%.

Easy to calculate the heat rise of rotors if you know car weight and stopping time............and rotor weight.

 

G35 Brembo (03-04)
Front: 21.1 lbs (324x30mm)
Rear: 17.5 (322x22mm)

G35 non-Brembo (03-04)
Front: 15.3 lbs. (296x24mm)
Rear: 11.3 lbs. (292x16mm)

 

Got them on!

I weighed all four rotors when they arrived 61.5 lbs. OEM rotors weighed 56.5 lbs a 5 lb difference. Thought the drilled slotted rotors would weigh less to my surprise that was not the case. So far I am pleased with look and fit, and quality. There is a better braking feel and the pads they provided appear to be low dust (no black wheels) and quiet at this point. Will keep you updated after a few more months of driving.