You're not going to make enough power to outflow the cone. I've had both open and close top K&Ns and it's sound. The open gives more of a whoosh turbo-ish sound while the close gives a growling sound.
The open top cone does flow better but again when you're talking about 1200CFM and 1300CFM while you're engine only needs a max of 800CFM it's not going to do much for performance. (Numbers pulled outta my arse for example).
Yeah I just bought the open sided to replace the closed ended one for my cold air intake because the top of the closed ended one is a pain in the ass to fit down there because of the fog lamp and it didn't seem like it was fitting very well. The open ended one fits much nicer down there since it is shorter. I just wanted to know because I don't want it to affect the performance with the CAI or not bring enough air in.
Your post seems helpful though. So the design is really only for the sound difference then?