I am looking to purchase a set of under pulleys from a person with a G35 coupe. My question is will this set fit on a sedan too?

Yep - same pulleys.

Might want to do some research on these. I've heard nothing but bad things about squealing belts and actual losses in HP after installation. Search the Tech section, bet you can learn a ton.

Any belt will squeal if the tension is not adjusted correctly. I've had my pulleys for over a year and found no change in performance. Manual trans should rev quicker because of the drop in rotating mass.

This thread is better for the Engine section and should be moved.

Yes they are the same for both. These are the only good pulleys to get for the VQ IMO. You won't see more than a few hp.