to begin with....its all starts with application....if you want it just to have a nice sound...and a cheap low cost intake...then just by and extension..and put a filter on it...or buy an arospeed or rs akimoto....etc...if you want performance...then there is two ways.... CAI or engine bay intake....ill give you some info on both....
CAI : extends to the bottom of the car....made with different materials depending on company.....AEM uses a ceramic coated pipe...which cuts out heat....even though it gets hot...once cold air flows through...the material adapts thus turning cold...the ICEMAN is a plastic....plastic blocks out heat too....however...when it gets hot..it stays hot, and when the cold air touches it, it gradually gets cold...personal preference is AEM... but ill stick with my ICEMAN...
SHORT RAM :stays inside the engine bay...there is a good and a bad to this....BAD is the heat that is being let out by the engine...it will take cold air to make more HP...and ur not getting any in there...unless u leave ur flood box and all tubing from bottom of car to the top...its a little bit better...but still not enough cold air..now the GOOD is that since its a "SHORT RAM" the time it takes for the air to travel from the filter to the engine takes alot less time that it does from the bottom of the fender to the engine...
to sum it up for nice cold air buy an aem...or a comptech ice box...or ICEMAN etc....nicest sound...aem..most hp AEM and COMP.. if u want a short ram ....AEM or DAC(which has optional extension)..hope it helps
