Ok guys... need a little help here... I bought one of the Eagle Horn Covers as discussed above. I chose the one without the LED (although I don't think that's relevant) and I have an '08 SERK. I tried to install it tonight and I can't make it "fit". The Eagle cover is nowhere near as deep as my stock cowbell cover so I can't get it mounted due to the depth of the horn itself. No matter which way I turn the bracket or the horn I can't mount the cover without the horn either torqued at an angle or up against the motor.
Obviously this works somehow... 
The instructions are straightforward... What am I missing...? 
My bike is the '09 SEUC. Chrome Dome's site said it should fit '92 and up horns.

I do not personally know when they changed horns, but unless they changed it for '09s it should fit.
Having said that, the fit was kind of trial and error to have it line up right. I looked at it on the workbench to see where it best fit behind the cover. You do not want the horn touching the cover, because it needs to vibrate freely for best sound. I moved the horn and cover around and around and ended up with about an 1/8" clearance from the horn to the cover. I may have used a rubber washer between the cover and horn to get a little better clearance.
I cannot remember if I played with slightly bending the mounting bracket on the bike to make room for it all. Mine ended up way closer to the engine than the stock one. Again, I played with how it was angled between the heads/cylinders and tried to center it so it had even clearance from both heads. The horn wiring plugs sticking out the back end up fairly close to the engine, which I feared may melt when it gets hot. I haven't noticed any melting yet.
I was discouraged at first, like you, but once I got it the best I could I tightened 'er down and went with it. Just make sure you keep the clearance between the horn and the cover best you can until tight.
Good luck!
Eagle Soars