Reviewed By j d (GAINESVILLE, GA) Reviewed for a 2011 Mercury Grand Marquis —2/18/2013 8:15 PM
Don't know about mileage increase but the Merc definitely seems a little more eager to go. Smoother acceleration and it sounds great. Easy install with the exception of needing star drivers to remove air sensor. Its a new GM and a great long term investment. Duals are next.