Hi.
I could really use some help with an exhaust issue on my 2014 Infiniti Q60s coupe, 55k miles, automatic.

This winter, I noticed smoke only coming out of one muffler. When I'm in park or at a stop sign/red light, the car gets very bassy and produces a minor vibration.
I thought exhaust leak, but 2 exhaust shops confirmed there was no leak and they could not confirm what the problem is. no rattling noises when they banged on the exhaust/cat and no lights on the dashboard, no rotten egg smell either.

Please share some expertise, I'm not sure how to proceed..

 

That's a hairy situation right there.. But this forum is not for Q60, it's for the G cars and they don't come with hairy mufflers.. I never came across one..

 

2014-2015 Q60 is basically a re-badged g37, mechanically identical. That's fiberglass dampening on the stock muffler which was already replaced with 2 aftermarket axle-back mufflers.

I suspect I have a clog after the Y pipe, on the mid-pipe where it is a Y, separating into the drivers side and passenger side resonators. Specifically 5" before the drivers side resonator, which is much cooler vs the passenger side being very hot. This is how i determined where the clog was.
The bolts are extremely corroded from winter/salt so it is going to be very difficult to drop the mid-pipe and inspect further.
I'm hoping I can cut out and replace the drivers side resonator, since it was cooler than the passenger side... but it was cooler 5" before the resonator so I'm not sure what to expect. The cats aren't rattling or producing any strange smells.