I am coaching a young triathlete with a lot of potential. He was hesitant to purchase a power meter, with the usual excuse of cost. I estimated this athlete had an FTP of about 400-410 watts. I was wrong, it was 448. He got the power meter finally and his first ride was a test for FTP. Here's where he stands now in his power profile in TrainingPeaks...
I think you can guess that when he saw this, from a single power file and test, that his confidence grew tremendously! He rates near a domestic professional cyclist, and his confidence will only grow as the numbers continue to grow.
If you're looking to get faster and better on the bike, consider a power meter. The data which comes from it can build confidence, and many times a belief in oneself is all that is missing from great performances.