Charged $129 for estimate. Failed to give me a written one when I went in to pick up my truck. Even thou I asked. Guess they did not want proof of the crazy amount they wanted to charge me.Said the catalytic converters had failed and wanted $7500 to replace them. Sent me to parts department were they gave me a $5500 parts estimate when I questioned them about why they were replacing all four cats and sensors and every nut bolt and washer possible in the exhaust system they claimed their mechanics demanded they price it out that way. Sounds like mechanics are paid on percentage to me. I found new magnaflow cats with gaskets for $415 and new O2 sensors $250 reused the bolts/nuts and did the work myself in a couple of hours. Really sad that a dealership is charging $2000 labor for a couple of hours work. NISSAN SHOULD PULL THEIR DEALERSHIP! Tested system and rear cats are fine it only needed front cats and sensors. O2 Sensor had failed at 104000 miles. I also installed new spark plugs. Less than $800 total in parts. I expect to pay more at a dealer, heck I can live with 100% more but not 700% this is theft. PS, my check engine light had only been on for two days. If you have a frontier STOP if the check engine light comes one, bad O2 sensor can get costly really quick.