I found that on 100psi and level 5, I was 16w in my favour on the FTP test. I tried level 6 but that worked against me far greater than the 16w. I use this set up for training consistency rather than the ZWIFT races. (There are a few people taking it far too seriously when after all it’s a computer game and a rather fantastic training tool. Get out of it what works for you. I think if I was after accuracy I’d buy a power meter/active trainer. Enjoy! 