I had a real hard time with mine a while back. I customized a screw driver that fit down in the plugs as far as possible and managed to pop them loose using both hands and all of the down force I could bring, which involved laying on top of the engine. When I reinstalled they got some anti-seize on the threads. I'M NOT AN EXPERT BUT: If you MUST drill them out then you'll have to pull the rear hatch for a straight and careful shot. I would mask off everything and set up a high powered vacuum next to the plug. Drill a hole just big enough to install a small easy out. Keep it centered! Don't let the bit drop down inside or you'll bugger up the adjuster screws. Work your way up in size as required. I'm sure a pro will be by for with some good advise.
Do you mean the aluminum taper-fit anti-tamper solid plugs (fairly easy) or the steel threaded access screw plugs (much more challenging)?
The plugs on the mixture unit that have the 3mm allen screws under it. They adjust idle mixture. I have a IM LM1 that has wide a band OX sensor to screw into the OX sensor opening, reads out direct Lambda air fuel ratio. Ago
