03 Eclipse RS

I am not a car expert by any means but I am trying
to learn. So this will have two questions and be
long.
1)  I recently bought a 03 eclipse RS from a private
owner. The car has an after market cold air intake
installed. From what I can gather it's supposed to
let more oxygen get to the engine which would
some what increase acceleration. The problem is
that it only seems to work when my fuel is low.
When I have less than a qtr tank left the car will
accelerate really fast. But when I have a full tank it
runs like a normal car. Any help on what is going on
would be great.

2) I want to install hid headlights. Is it better for me
to just find an individual projector made for hids and
get those put in or can I just buy spyder projector
headlights and then just put the hids in those. If it's
the former of the two how do I go about finding the
right projector for my car.