So I had a headlight bulb burn out on me. I change my bulbs myself and when I change them, I have to take the entire headlight assembly out. I don't have little hands to get back behind the headlights to replace the bulbs, so I remove the entire assembly. When I took the passenger headlight out, I looked at and examined the air intake. I followed the tube, there's an small opening for air to be taken in the engine compartment (Looks like a snorkel). If you follow it further the intake tube passes into an opening which leads to a space forward of the front right wheel. (Passenger side for US models.) There is a huge baffle in this space. (Large white box) I removed it to examine it. it's a large box with several chambers in it, and there are 4 or 5 small holes in the bottom (these holes is where the air is drawn through - Extremely restrictive) I did a search and found this Priuschat post http://priuschat.com/forums/gen-ii-prius-technical-discussion/97156-whats-air-box.html Other searches about Cold Air Intakes,showed that the Prius doesn't like CAI's and has resulted in errors in the Prius's electronics, and irregular MAF readings, which doesn't allow the ICE to run. So I wouldn't recommend a true CAI, but removing the baffle might be an option? As I was working on the car I was thinking, why not try to drive the Prius without this restrictive baffle instead of a CAI? So I removed the baffle last week, and since then I've noticed that hills that the Prius really struggled to drive up before, had to problem going up now. Also the throttle response seems smoother and I've noticed I don't have to mash on the gas as much to get the car going. I've noticed a slight increase in Fuel economy ( like 1 mpg more... but still an improvement.) Has anyone else tried this and and any issues, or noticed any improvements? Anyone else wanting to remove the baffle the first thing to do is remove the right side / passenger side headlight. Here is a link to a video that shows how to remove the headlight assembly: (The passenger side requires that you remove the intake snorkel by removing one small push pin/clip that holds it in place, using a flat head screwdriver, gently pop the push pin up, and then remove the clip.) Once the headlight assembly is out, remove the air intake pipe, then you will need to remove the bolts that hold the baffle in place (all are 10MM). Two bolts from the top, one nut in the front, and another bolt by the wheel well plastic liner (to remove this bolt you'll need a flashlight to see it, a ratchet, 10mm socket, and extension to reach it and get it out.) Anyone who has removed the baffle, or wanting to do this mod please post your questions, results, issues, or successes.