Rs tuning or Ktec to build it, if you build it yourself you'll still need Rs tuning, Ktec or TDF to map it.
They can drive as standard, can be reliable and great fun. On the other hand, they can drive like ass, Could be unreliable and you'll get pissed off and try selling it 6 months later.
Many people love it then sell them for next to no money, might be worth waiting for a prebuilt one. Both Adey and I have built ours ourselves and although no less reliable, it means we know what's broken if/when it breaks.
Ours are both running higher boost that we should on a standard bottom end, adey's has done 10,000 miles at 275bhp, mine 1500miles at 273bhp and we haven't opened up the engines yet