In 2003 they extended production by a month or two because of the 100th anniversary. To me that would mean they produced more in '03 then other years. 

Ride Safe,
Fired00d

So you must have knowledge that they did not increase production capacity after 2003 which might have increased production without extending the number of production days.
I will bet that if you look at the number of bikes built in 2003 and on that you will find a steady increase in production.
Tom Bergmann, chief financial officer and head of strategy, said: “We have taken 25,000 units out from our production, but we’ll still ship around 300,000 motorcycles this year.”
U.S. sales of Harley-Davidson motorcycles were down 12.8 percent during the first quarter. For that reason, Milwaukee-based Harley-Davidson announced in April that it planned to let 370 unionized workers and 360 nonproduction workers go nationwide. The company wants to ship fewer bikes than it sells. That would be a return to the business model that served the company well during the late '90s and the earlier part of this decade, when people were waiting as long as six months for a Harley.