not quite true Jet, we are forever trouble shooting cars that we have not seen previously most workshops will do any work that customers are prepared to pay for, at present we have a BF XR6T that we have never seen before, it was brought into us as he can not get to the bottom of his issues since the bottom end was replaced after a blow up, so far we have found that the cylinder head temp switch which normally fits in the rear of the cylinder head has been broken off so a new one was fitted into an exhaust manifold stud so it is getting full exhaust heat into it, the turbo actuator hoses are on incorrectly, the turbo housing is wrong and the boost hose has cracked from the exhaust manifold heat, the front housing does not have a reference nipple so boost for the actuator is being taken from the inlet manifold, there is mechanical noises from the cylinder head and possibly a valve timing issue, wiring looms have broken plugs, incorrect boost pipe joiner on the throttle body and the blow off valve is fitted the wrong way around.