Looking for some info with a two fold question: I have been looking into air intake for my 05 and someone told me , that all it will do, is increase turbo sound not neccesarily performance:

1)will it help the truck or is it for sounds and looks?
(I dont mind the sound increase, as long as it is noticeable)

2)What is a good brand?

TIA

use the search feature many discussions on this.

try this for starters:
http://www.dieselplace.com/forum/showthread.php?t=75609&highlight=stock+airbox

After doing some more research i have found it'll give me morte sound than noticeable performance, and that led me to another question;

I noticed the afe filters are in a closed box while other brands are a more open design. Which is better or no big difference?

AFE makes a very nice intake system. I ran one on my 04.5 LLY. I noticed no difference with mileage or performance. Its alot of money for some louder turbo whistle.