I Purchased A Used 2005 Chevy Duramax With 27,000 On It .is It Worth The Money To Put A Chip, Bigger Air Box And A 4 Inch Exhaust? I Am Looking For A Little More Power And Fuel Mileage.whats The Best Chip Air Box And Exhaust To Buy. I Recently Sold My 1997 Gmc Sierra Turtle Diesel And It Was Almost Impossible To Find Add On For Power. With 100,000 And 5 Injector Pump Failure It Was Time For The Upgrade ,need Some Advice!!!