I completely forget the weight of stock 16" GTS wheels, isn't it around 25lbs or so? Now I'm not certain if that would be without tires or with.. either way, there is a guy locally selling a set of 18" Motegi FF7 that are black with silver lip for a fairly decent price, but no rubber. He thinks they are 25lbs, offset is +45 and backside setting is 6. I think the offest is fine with our cars, and if the weight is the same as a stock wheel then the only loss is the comparison is size and that going from 16" to 18" may be a tiny bit slower but probably not noticable.