Barely working

first 2 years at this company was an absolute slog, with extreme unresonable deadlines and politics. Now all of a sudden I am SME of an area and work consists of just providing info to colleagues, minor amount of code, code reviews, architecture guidance, meetings. I only work 4 hours per day now but still accomplish more than I used to with 8-12 per day. Manager is new so doesnt know enough to really know how much work im doing. Im feeling quite guilty about this. Should I be going and finding new mess to get involved in, that will fill up the other 4 hours? I feel like im getting my time back after slaving away to get my former manager promoted by delivering projects with unreasonable demands. But my work ethic, my internal drive, says dont slack off, someone wil lfind out and karma will catch up with you. Meanwhile I am finally getting time to exercise and soend time with friends and fmaily. I am in the best shape of my life with low BMI, and Im building new skills, reading a lot of architectures of other systems.