Recently I read somewhere that the spoiler was (I think) part of the P01 performance package? And that it came with stiffer springs? Is this true, or is the spoiler just an option? I would love to know more about it because I have been looking at buying a G35 coupe and have only been targetng ones with spoilers for the visual but also for potential benefits in the trim that the spoiler comes on. Thank you!

2006 had a few other options but the rear spoiler was still part of the aero option.

Check out this .pdf.

What is the 18hp difference between the engines in the automatic and manual?

Rev-up engine vs the regular VQ35DE.