nothing is the best. It's all about what you like.
Yes agreed. But if you want my opinion get a rear lip that is as beefy. There is one I have seen that looks like it has a diffuser if the middle portion is painted black. SOrry forgot the name.. someone here will tell you. LOL but ya search around even on google you will find something of your taste.
I did the GFX on mine, well after installing my Tanabe axle back. I love the way it looks. I don't think the fact that you are running the HKS has that much to do with it. Pick the rear lip you like the best and go with it. Tips on aftermarket exhaust don't look that much different.........
I prefer the look and the sound of the F-sport exhaust. I think the thick chrome edge of the exhaust looks more expensive/classy.
2011 IS350 Matador Red Mica with spoiler, Nav, F sport exhaust, tint, Joe Z Intake in Blue, 8500 x50 radar detector, blend mount, smart card key, rear F sport sway bar, and steering damper.