I currently have a RRS and am looking at re- mapping the engine, thus does anyone have any experience and any recommendations?
I have found DMS Automotive who claim to increase bhp to 298 and improve mpg as well?

Any thoughts or advice?

I remapped my old 2.7 but I find the 3 litre is perfectly fine without it. Of course that's just my personal opinion. The one thing you must remember is that it will void any warranty on your engine & drive train and it will also void your insurance unless you inform your insurers. 2013 Discovery HSE Luxury - 3.0 SDV6 - Santorini Black
2013 Evoque 5 Door Pure Tech SD4 - Orkney Grey with Panoramic Roof (Mrs E's new baby)

GONE - RRS - 3.0 TDV6 HSE - Santorini (2010)
GONE - RRS - 2.7 TDV6 HSE - Java Black (2007)
GONE - Porsche Boxster S - 3.2 - Black