I just installed a Thorton Chevrolet Performance Chip tuner. I got the stage 3. $99.99. Been in for about a week. It has given the car better pick up and smoothed out the idle. As for better gas mileage? Wait and see. I did a cleaning of the intake and fuel system and fresh oil change. I have a 2006 2.4l and I'm thinking about a cold air intake next.

 

Welcome to the site, I’ve had several aftermarket air intake systems, the best one I’ve ever had is a K&N drop in filter to the stock air cleaner box , it still pulls fresh sis in from outside the passenger fender and didn’t cost $300.00.