I have this exact knob. Was one of the first "mods" I did. Took about 10 minutes to swap out the factory knob. I did use a couple drops of blue locktite. I'm not a fan of the newer leather appointed knobs. As far as size, I never have noticed a difference. I'd say go for it - one of the easiest...
These Focals are on my list for my rear deck. How do you like them? Did you punch small holes on the deck covering to improve the volume coming from them?
I considered this before using a different set up as I have a shallow box 10" pioneer sub in another vehicle. In my opinion a decent 8" isn't going to fit. There's zero space down there. I went with a self powered 12" in the trunk and sourced the input from the rear speakers. Works great for me.
This OP. I have the one you linked on my non-boosted 21 for the passenger side. Quick, easy install. I get a few teaspoons worth of oil every 5,000 miles
So true. My factor is 2X. I've told my son take however much time you have planned and double it. It's hard not to get frustrated at times but I remind myself it's all part of the game.