RRE did it and it cost like 6grand total. and they're a shop. i remember alot of talk about most of the parts being custom fab for the job. AWD on the 420a isn't very easy and even if you pull it off you need alot of power (turbo or alot of NA power) to displace the added weight. a GSX weighs about 800lbs more than us dry. with a driver it's prolly about 1000lbs more.