What are the exhaust dimensions where it goes up over the rear-end on the 91Z28 compared to the 92RS?
I found a good flowmaster muffler on a 92RS and was going to cut it off at the bend or further up and attach it to my 91Z since its shot.

 

I think the Z is 3'' in dual 2.5'' out while the RS is 2.5'' in dual 2.5'' out. Please correct me if im wrong.

 

I believe that's what mine was. But since its the factory it's not a true 3 inches over the axle. More like 2 3/4 with all the bends and dents in it.