We sold most of the brands, like Invidia, Kinetix, Berk, Motordyne ART, but I'm pretty sure there will be more guys here to chime in with their recommendation. I'd personally go for Berk HFC because the car doesn't smell so bad with them on, you can still leave the windows open unlike on my GTR with straight through system and because it comes with the brackets for the OEM brace that eliminate some of the vibrations transferred into the cabin, if not most of them.
Oh, if money is not a problem, Motordyne ART pipes, always!