I know lots of folks here are on a budget but there are two reputable performance shops that make custom Turbo Back exhausts for our cars and have no problem shipping:
Road Race Engineering (California)
Certified Muffler Performance Exhaust (Florida)
There are plenty of other Mitsu specific shops that will be happy to build an exhaust system as well so ship around. FWIW, I currently run an RRE turbo back exhaust on 182. Granted, it's 2.5 " until it clears the Oil Pan then it opens to 3" straight back. No Catalytic Converter, no Test-Pipe, just straight back to HKS Carbon wrapped 4" fartcan. Fit is superb as are welds and I couldn't be happier.