can a muffler with a 2"inlet be installed on a car with a smaller sized exhaust

can a muffler with a 2"inlet be installed on a car with a smaller sized exhaust

I imagine it could be done with the proper reducers but you're going to have trouble with the O2 sensors .

I don't see a problem with it if the right reducers are used as mentioned, though a gradual size change would be better. O2 sensors are well upstream of the muffler, so they won't see any significant change IMO.