Go with roverron. 2 years now for me & it's well worth it. No, you don't need to uprate anything, just follow all his advice & you'll be fine. Yes, you might get a little more from a good remap as they can alter the boost whilst roverrons box deals solely with fuelling but it'd be less than 10% better & as you say around £400 compared to less than £200 for roverrons gizmo. One thing a remap can't help you with is the maf degredation that afflicts all freelanders after about 30k miles but roverrons synergy 2 unit comes with built in maf compensator - big bonus. Also fit an egr bypass too & you won't be disappointed. Do it now, & you'll wonder why you didn't do it sooner.