Its a good idea to get it mapped pretty soon after fitting the turbo because you may be running too much boost with the wrong mapping, but as long as you don't thrash it with incorrect mapping it'll be fine. I'm taking mine to rs tuning in leeds basically because he's done loads of these hybrid tdi's and really know's what he's doing. I know he can get 240bhp and 380lbs ft of torque from them, but its a bit smokey so he turns it down abit to 230bhp and 350lbs ft. When I get mine done i'm going to get a little box as well to allow me to switch between different maps. Paul at rs will do this for you for a cost not too much i dont think. I'll have three maps then, a sort of standardish map around 140 bhp with good fuel economy and when other people drive my car, a fast road around 180bhp for dry nice days and the one I will probably use most, and a flat out map with lots of smoke around 230bhp, it'll just give it some flexibility, and should
help keep the gearbox in one piece, as i'm nearing 100,000 miles now and I think anything over 350lbs ft of torque may cause problems, but we'll see. By the way what clutch are you using, thats what I need next then I'll fit turbo and go get it mapped. Good luck with it all, And while your fitting you turbo, get the garage to clean out your inlet manifold and block off the EGR too, as paul at rs tuning will map out the egr too to stop the CEL coming on.