JDM cat back compatibility

[murphay]

hi all, i have a 95 dc4 and need to replace my cat back soon.

ive seen some jdm catbacks for sale, mugen twin loop and spoon n1 but after reading on some other threads and found out that theyre not just bolt on.

i know there is a difference with audm and jdm exhaust systems
audm type r 450mm and gsi/vtir 300mm
jdm type r 300mm (could be wrong)

1) first question is does that mean the jdm cat backs will fit with no gaps because the cats are same size?

2) second question is it might be cheaper buying a type r full exhaust. so i want to ask if type r headers are compatible with b18b engine?

thanks any help to steer in right direction would be appreciative