Reps will be slightly heavier, but not enough to really make a difference to normal driving. If you find a set that are 18 x 8 ET45 they will be perfect, sitting 12mm out further than OE wheels which will fill the arches nicely.
I am looking for some to go on the vRS, but I can only find ET35 or 42 which will sit the wheels out to far, IMO.