depends how you do it.. if you get the old ones out, you can just pull the new ones through after grinding down the head of the bolt a lil to clear the hub.
5mm you will regret man.. you can EASILY fit a 15mm up front. 10mm if you wanna play safe, but it'll still be sunken in. 5mm will be wasting your money, IMO.
Kics Wheel Spacer - 15mm / 12x1.5mm / 5 x 114.3: Evasive Motorsports | PH: 626.336.3400 Mon-Fri, 9am-6pm PST
or just buy the longer studs.. run some project kics open ended ( or any open ended) lug nuts and you'll be fine with any set of wheels that you choose.