4" is right there at the breaking point for needing a new DS. If you didn't get a new DS, you would have to have a MML and a TC drop. Personally, and this is just me, I would do the lift and when it is finished take the measurements to buy a new DS. At Tom Woods it would roughly run you about $350 or so. It would give you peace of mind and a more complete set up. But there are several ways of doing it like I said. But 4" is pushing it a little.