some people claim this is "the best mod you can do to a UKDM teg"
Full JDM exhaust swap is.
From the manifold back its the same system. Bar cat length difference. Only thing special about jdm systems is the manifold. 98 spec that is.
Best/ easiest mod would be a spoon ecu. Noticed a great difference going from std jdm ecu to spoon one with b18cr. Search it on here there is a good write up with dyno comparisons.