Originally Posted by calvin2376

The F-Sport rear sway is a must-do mod, regardless of whether you choose to do anything else. I honestly wouldn't spend a dime on any other mod until you get the F-Sport rear sway (I'm talking about a 350 because that's what I have, didn't see anywhere that the OP indicated which IS he has, I can't speak to the improvement on a 250).

Otherwise, it all comes down to personal preference. I'm in the same boat as you and am only doing relatively inexpensive mods, so for me that includes F-Sport rear sway ($157 before shipping on Sewell, can install yourself), red-outs, HID fogs, 5000K low-beam bulb swap, new front grille insert.