In 2009, I took my Nissan Altima for an estimate since it was running poorly. They stated that their "Best Mechanic" said that my car needed a new Engine, a Catalytic Converter and some new sensors. I was shocked that their estimate was $5,400 (not including taxes and any other miscellaneous charges).
I took a written estimate from the Nissan Dealer and then went to the Meineke Dealer in Lodi, New Jersey, which replaced both the front and rear Catalytic Converters, a piece of the exhaust pipe, two sensor and one Ignition Coil for only $2,500. The Meineke Dealer told me that the engine was fine!!! As of October 2013, my Altima is running great!
BUYER BEWARE!!