This topic should be fun :)
I use the Genos cap, and go thru the fender well, with no issues, tried it a couple times with ziplock bag to make sure going thru the fender worked okay before getting the Genos cap. I did it thru the top the first couple times,
IMO its a PITA going thru the top, just not having to take the intake off, but the whole process thru the top, and of course opinions vary :B
One thing you can bet, is that service centers or dealers do not mess with taking the turbo intake off. I'm sure there is some mess involved, but they surely drop it out thru the fender well.