cool 550watts is massive!! can you hold that all the way up? and is that working at 85-90% of max effort?
just so you and slyv know when i'm calculating watts per kg, you went up by 0.1 on your previous effort from your time of 5:10, i'm adding the weight of your bike on top of your bodyweight, and using 8kg for your bike, if its any different let me know and i'll adjust it.
i reckon sub 5:00 is in the bag, do you need someone to motorpace you up to the top. you've got to be doing 27kph average right?