Just back from the dealer. Says OEM pads are semi-metallic, front & rear.

 

Further to having different types of ThermoQuiet pads on front vs rear:
Sent an email off to Wagner support and got a prompt response, also a support phone number:
The upshot is that ThermoQuiet rear pads for the 2004 G35 with single piston calipers are ceramic and with two-piston calipers are semi-metallic, therefore fronts and rears would be a different material depending on the caliper set-up. Also said that according to their info, rear OEM pads were ceramic for single piston calipers, semi-metallic for two-piston calipers. Sounded more detailed and more credible than the person I talked to at the Infiniti dealership.

 

Not sure what happened to my last update, will try to resubmit here:
Further update to Wagner Thermo-Quiet front and rear pads being different materials:
Sent an e-mail off to Wagner support and got a prompt response including a support phone number. The upshot is that for my setup (2004 G35X floating caliper (non-Brembo) and single piston rear calipers) the front and rear Thermo-Quiet pads are of different materials, the fronts being semi-metallic and the rears being ceramic. If the rear calipers are dual piston, the rear pads would then be semi-metallic. The person I spoke with said that according to their information, OEM pads are this way as well, i.e. for single piston rear calipers, rear pads are ceramic whereas for dual piston rear calipers, rear pads are semi-metallic.
The explanation from Wagner seemed to be more detailed and credible that that received from the Infiniti dealership.

 

How do I get that OEM brake bite back? I bled the brakes really well, but I've never been able to get it back. I'm using centric pads and rotors.