My car ran perfectly with just a stage 1 remap then I did a stage 2 conversion on it and now I have loads of grey and blue smoke coming out of the exhaust but only when going down a hill and only at low (below 2K) revs, also if I brake hard which clears on the flat after a few seconds. Normal driving on the flat or going up hill is fine, no smoke on idle or when booting it. AND Since stage 2 I've also got a very rough idle, sound like I'm revving the car. AND The power cuts out between 1.2k and 1.8k revs especially when cold, it's un-drivable cold. No codes showing, I did a home made smoke test and no vacuum leeks showed. Smoke = Turbo or Rings? Idle and running = ???