Sunday I did the Tour of Watopia (not because I care about finishing, I just wanted to do a competitive ride). Anyway 2 of us got detached from the lead group and rode near FTP for 45 minutes with maybe z3 HR.
So I'll bump up my FTP, which is artificial since its an estimate, but then I'll bump it up again because of the 'indoor modifier' of -8%, so my best power of the year is 40 watts below my actual FTP. I'm sure if I went outside fresh and tested, I could hit that, I just think its kinda silly, and and another reason not to throw the number around.