Noise and tuning of the air flow in. It allows the incoming air to slow and lose turbulence and large particles before being pulled into the second airbox. Some people add extra holes to the filter box. This increases noise quite a lot, I have not heard of any conclusive proof of it adding performance, in fact messing with this system can reduce performance if you don't also make the exhaust breathe better.
A good starting point for tuning questions on the T3's is the venerable old "Hinckley FAQ" and the "Classic Tuning Tips" document we have copies of in our downloads section (
Click Here ).
HTH
[ This message was edited by: MickMaguire on 2003-11-21 06:39 ]