not sure on the petrol one, the diesel is a relativley simple repair you just need to be carefull when cutting the seats that you dont get any swarf from the head in the bore. what i do is use the cutter which pushes the swarf to the outside of the injector seat. then using a bit of threaded bar ground down to the same size as the injector nozzle, poke that in the hole and use compressed air to blow the swarf out
the hardest part is refitting the inlet manifold it can be a real bitch to push it back into the inlet runners level! there is two 10mm bolts down the back of the engine holding the manifold on which are the ones difficult to line back up when re fitting the manifold