So when I replaced my bad battery, I saw the driver side firewall was oily. Just my luck the brake booster is now leaking. Can't say I'm surprised at 270k miles. The master cylinder was replaced 3 years ago. So I went shopping and picked up a new ACD hydro booster, new 2020+ front rotors, new 2020+ power stop pads, new stock replacement brake hoses, new rear guide pins/boots and new stock powerstop rear pads. Should be installing all this tomorrow including my 2020+ 4 piston calipers. I have had the new calipers in the garage maybe 12 months now.