6x10 Z4 with 5min Z2 in between (zwifting). It's weird, I have sustained 93% for 60 mins straight and even doing around 95% like I did today is pretty comfortable, but I have a hard time getting comfortable at 250-255w as far as cadence is concerned (either have to spin faster than I like or slower), going to have to get the tighter ratio 12-23 cassette on and see how that helps. All this to say that I have kept my ftp at 250 because I haven't proven to myself otherwise that I can actually do better.