Strangely enough I have just had one of these come my way via my MOT garage, initially multiple misfire codes logged , GSF coilpack fitted which then generated a load of spurious fault codes similar to the old NGK plug faults which are well documented here , it appears as though ECP and GSF are selling poor quality chinese clone coilpacks in GM boxes, giving the impression they are genuine, the way to tell as I am led to believe is that a genuine coilpack has a barcode top and bottom of the parts label, the clones don't have the bottom barcode?

The garage that I gave this info to are now chasing up through Trading Standards so will keep you all informed on the outcome.