I haven't put a hypermax on, but for any turbo work, it would be easier to lift the cab up and set it on 6" blocks to do the job, and that would make it a prime time to either replace the cab mounts or give it a lift. If you are going to put a turbo on , at the very least you are going to want new cab mounts to prevent contact due to sagging cab mounts, and trying to get your hands in there with saggy cab mounts is a nightmare. To get the things seperated to block it up chances are you will end up cutting the rear ones, soo, might as well buy new ones, so it just becomes a matter of which will it be, new cab mounts or , new cab mounts and a sack of hockey pucks for a 1 " lift, or a 2" lift kit.