This is what I have found so far:
I believe the exhaust manifold is the same on all B18 Civics and Integras
DC2 and EG hatch are with shorter 2570mm wheelbase.
EG sedan, EJ1 coupe, EK sedan, EM coupe, MB6 and MC2 are 2620 wheelbase.
This means the cat converter + pipes to rear LCA is 50mm different and I believe the cat converter is the difference. People mention short jap converter and long UK converter.
Also DC2 is 4380mm long, EM1 is 4450mm, MB6 is 4325mm or 4330mm, MC2 is 4425mm.
DC2 exhaust with the longer EM1 cat converter or EM1 full exhaust may fit MC2, but I have no way to test that.