What is the difference between a short ram aftermarket intake
for example:
http://focus.c-f-m.com/index.asp?Pag...ROD&ProdID=381

and a regular "hi-flo" aftermarket intake such as:
http://focus.c-f-m.com/index.asp?Pag...ROD&ProdID=381

Performance gains seem comparable. In general terms, Is there an advantage with one over the other?

Also K&N makes one:
http://focus.c-f-m.com/index.asp?Pag...ROD&ProdID=901
Seems pricey, but claims that it is quiter than competitors intake systems. This is a plus for me, I'm really not too interested in increasing noise with my performance. Is this true, are the metal intakes loud under throttle?

Sorry in advance for what may seem to be newbie questions, but
I have a few bucks (thanks Uncle Sam) so I thought I might do something fun for myself. Open to suggestions.