Slip on muffler question

[Radioone]

I recently purchased a 4 into 1 exhaust for my 750 K4. The outside diameter where the muffler attached is 65mm. So far the largest diameter slip on muffler I have found is 54-55mm. Is this a common problem, View attachment 7936and is the best fix a short reducer pipe or are there other options? Thanks.

 

[amc49]

The norm is usually 2 1/4" or around 57 mm.