Be careful here, why do you want to replace glowplugs, fault codes logged for glowplugs perhaps? Head looms on these go high resistance flagging all sorts of codes for injectors and glowplugs, in answer to your question about removal, they are only torqued to 10 NM so no problem removing, I reckon on a full VCDS scan on 10 PD engined motors, at least half would flag 1 or 2 glowplugs down, does not affect running or starting, If you are going to do the plugs, advise customer that while you are in there it would be wise to replace head loom,but, around £80 if I remember right, they will probably refuse