If you are wanting to put 17" rims on the rear, then yes, you do need to make a change for them to clear. You will have to get new rear brake lines with shorter banjo fittings, the stock ones are very tall. Even after doing this, you will need to check clearances closely. We needed to grind the bolt head down even more to clear 96 17x13" rims we were using for racing on our 02 GTS. They sell a kit, do a search to find out where to get it, I forget where ours is from.
Jeff