Welcome to the Forum...
Me personally, looks-wise... I would NOT want my EX to have FX Rims on it.
So are you wanting to upgrade to factory FX 18's... or 20's ?
18's aren't much of a step-up from 17's...
EX35 17's = 17" x 7.5", 45mm Offset
EX35 18's = 18" x 8", 47mm Offset
Bolt Pattern = 5 x 114.3mm
Assuming you'd want to go up to a 20...
FX35 20's = 20" x 8", 40mm Offset.
Bolt Pattern = 5 x 114.3mm
Then what you'd have to do is, find a comparable size of 20 inch Tire so that your Speedo isn't out of whack.
Lots of guys feel the way you do about the 17's >>>
post4611797.html but this guy wanted to upgrade to 19's.