One of my boost plugs was a bitch to get out. I tried a big breaker bar and almost stripped it out. I ended up getting a punch and a big hammer, and hitting it at a low angle to break it loose. Took a couple good whacks! I was worried I’d have to drill it out this winter...but once lose, fame right out.
Thanks Dave. You thought yours was a 3/4-16 plug right? I have the adapter but it looks a little big, it might just be an illusion though. Figure I'd get it out first and see what size it is.