Well, here is the sum of my knowledge on the NA engine, listing the mods I have done :
1. Needswings CAI ( single, dual is overkill on an NA )
2. 74mm throttle body
3. Eurotune engine tune.
I think ( no dyno ) I am somewhere around 260 HP with these mods.
From EVERYTHING I have read, exhaust mods return very little on the $ spent, although I did install an OBC Racing catback ( Borla Chinese rip-off ).
The only thing I might still do is a brake upgrade with SRT6 front rotors and calipers.