Well let me start with my trip, I went about 250mi and traveled about 50/50 interstate/local roads. This modification significantly improved the get up and go of idle and roll on. On the interstate traveling about 70-75, I could easly get by semis with just a turn of the throttle passing them quickly at 85-90 (I don't like being anywhere near them). Gas mileage for the trip average about 52 mpg, that's pretty good. I checked the plugs today and they looked good, no indication of running lean. I'm very happy with performance.
There are two downsides, this noise is much more than stock, and I found I had to wear a elastic band around my leg. I found that if your pants are a little baggy and you keep your knees in tight, it will suck your pants material in. I actually had an idea of pointing the opening down but I had this ride planned and didn't have enough time to get done. I should be able to use the existing cover for my upgraded modification.
To answer a few of the questions, first I will be probably give more detail later in the "How To" part of the forum, I have to figure out how much detail and pictures I need first.
Here is a link for a comparable dyno, I'm not going to do one. Just hit the green view button when you get to link page.
The main reason I put the intake where it is, because I didn't want to worry about rain getting in, water won't travel up. I also thought about putting slots around the 900 emblem but it's right above the filter. I know a number of aftermarket filters do that, but I didn't want any chance of water getting in.
I intentionally blocked off the stock airbox, I didn't want to suck in any hot air from between the cylinders, the cooler the air the denser the charge. I even insulated the back of the aluminum with cork because of it's good heat conductivity. I started out with a 6" round straight sided filter similar to what S&S uses. The problem with that is there wasn't much room for air to get to the back side because of tight clearance. Also I found out that wouldn't work anyway because the filter isn't center on the cover circle emblem, it is offset, so it didn't clear the cover. The tappered filter really fixed both of those issues. The filter is a custom K&N filter that I found while looking at their website. I think the taper aids in transitioning the air flow gradually instead of a sharp 90 deg turn into the throttle body. The less turbulent the flow (causes hi pressure drop) the better the air flow into cylinder should be.