Removing old Injector Seats from Audi A4

I have a 2001 Audi A4 1.8T.  I'm in the process of overhauling the injector an PCV systems as the injectors were leaking, and the PCV system is leaking all over the place after > 220,000 miles. 

There are several articles talking about how to remove these, and there are strategies like removing them when the engine is hot, using ethanol, acetone, and using the right hex tool (2001 is 20mm), however these strategies fail spectacularly at this age as the cups just disintegrate because the plastic has gone brittle. So don't waste your time trying to find a 20mm tool at that point. It doesn't matter what tool you use they're nearly impossible to remove cleanly at that age.

The strategy I've come up over the last few hours that seems to work is chiseling out the cap on the top, and the tail at the bottom, and then grinding out the bulk in the middle with round wood sand paper moto tool attachment, and then using a round steel brush moto attachment to grind out the plastic bits from the threads. There's a strategy to the steel brush tool, you basically use speed 4 or so, and then push straight down into the thread until you can see the metal, and then move to a new spot. After you can see the threads, can can press down a little more to grind a bit into the threads, the threads sound be ok with this. Then you start picking away with a precision flat head screwdriver. If you're lucky, the heat from the metal brush detaches the plastic from the epoxy so you can carefully peel away a few rounds of the plastic from the threads. After all the plastic comes you, the really time intensive part starts, that's picking out the epoxy that's glued to the threads. Here you have to use the precision flat head screw driver and leverage against the edge of the cup and start scraping following the threads. Eventually you'll figure out the amount of pressure you need to remove the bulk.

After it looks good, you'll put the new cups in and find out that it sticks in certain areas, and now comes round 2 of the scraping with the screw drivers.

HOURS of fun. After one night I'm half way done <sigh>. After all this work I'm chucking my new plastic cups and just ordered a set of billet cups. NEVER AGAIN.