I might be wrong here, but what does GTS get over GT that I would want to spend $5k on? Interior gadgetry? - no, Leather - no, HIDS - mmm maybe beneficial... 17"rims and tyres - well yeah, but I could find nicer (IMO) ones aftermarket...
Is there anything else, suspension or something of actual benefit? Or just stuff that adds weight and cost but is not necessary (IMO)
I have not looked into the specs, so am just unsure of what all the differences are