There are people out there saying it is now possible to upgrade the Stealth suit Mk II to the Stealth suit Mk III via the workbench. I know there are PC mods, but as far as I know there is no new patch (PS3) to upgrade it beyond the upgrades available in the X-13 testing facility. I do know I wouldn't mind a higher DT, but my Sneak is already 100, PER is 9, AGL is 9, and Sneak speed is fine. Although adding the implant (Can't remember which one it was exactly and I am not motivated enough to look it up right now) that increases your sneak speed further seemed to have no effect.