As far as the race engines go I don't put them in the same category as a pleasure boat what so ever.... Yes the racecourse is the ultimate endurance test on a piece of equipment but it's not a similar environment in my book when it comes to headers....
How many hours does a race-boat put on every season, (1-2 hrs per race and testing?)20 hrs per season max? How many hours does a pleasure boat put on every year, 40-75 hrs on the average with much higher numbers in the southern states? How many heat cycles do headers on a race engine have to endure, 2 per race (cold-hot-cold)? How many heat cycles does a pleasure boat have to endure, multiple per day/per hour?
It's not apples to apples in my book...
Besides, a number of race boats are running the tractor pipes.
The bottom line is a lot of people see what they wanna see and hear what they wanna hear!