I have a '05 Infiniti G35 that I recently purchased and am anxiously waiting for my Borla Cat-back exhaust. I started to think about getting headers as well since the exhaust is coming off why not go back to the engine? So I'm looking at DC Sports 3-1 , Part No. NHC4201 for the 2005 Infiniti G35 Base/Standard. And just want to make sure that it will fit up to the Borla part #140093 Cat-back system.
If anyone out there knows about the fitment or anything about either the headers or exhaust and has any pointers hit me up, as I am always looking to learn more.
Have a good day all

 

The headers do not connect to a cat-back exhaust, the cats do. Headers are a pain to swap with the motor still in the car, the amount you'd pay in labor for a few hp is not worth it IMO. Since the cats are the most restrictive part of the exhaust system I'd look into getting HFCs or Test Pipes.