Well....I have pipercross filters.......I am thinking about going back to some sort of air box or creating my own. I have found out from VTWIN tech guys (mainly JD Hord) that Vtwins like the pressurized air better. Which means they like a air box better than just open air.
I had a plate that went on the throttle bodies to create a kinda pressure area between the tank, frame, and this plate. Well, I decided to take it off and put it on the dyno again...lost 3 or 4 HP......THAT WAS THE ONLY CHANGE I MADE! Same dyno, same guy, same kinda fuel, etc.
That is odd. Most drag bikes have the cold air induction ( open filters) on their bikes. I have never seen an air box on them and they are HP crazy. I wonder if the location of our air box has an effect on the amount of air coming through the intake. I read that the newer bike (sv's) have a 9 liter air box. I dont know what the 03's have. Did you remap after the changed filter set up? That could have been an issue with running rich.