[Rockster]

Does anyone know what’s rattling? I have a 2016 challenger RT and ever since I got mufflers added I’ve started hearing a rattle when I slowly accelerate and it gets ready to shifts then when jt shifts it goes away then comes back again when it’s time to shift

My WAG would be an exhaust holder/bracket or clamp was left loose. Another explanation is the mufflers in being added somehow has at least one muffler touching something.

I could also believe based on how you describe the behavior of the "rattle" -- it is not too far fetched -- the noise is an exhaust leak.

 

[Rockster]

Oh really? I checked everything under the car nothings lose. So it’s a leak?

If you are sure your check under the car missed nothing loose then a leak becomes more likely.

Forgot... More likely but this assumes besides nothing loose you did not miss some exhaust component touching another part of the car. The exhaust system is pretty tightly integrated with the rest of the under body and running gear. If the install was sloppy...