Bill - This here is the sketch I have for the exhaust. Your muffler doesn't look Ed Zachery the same. Are you the original owner? I highlighted the resonator, just ignore that. But in any event, I believe Mitsu could downsize that muffler quite a lot, reduce their cost, and still have very acceptable exhaust noise. Course, they have to meet dB regulations ... maybe this is the least expensive muffler they could source to meet requirements.
CAT / MUFFLER / RESONATOR
View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)