I was told that it isn't an easy conversion to twin exhausts as the exit through the inner wings is in a different place on the near side and there is a new hole to cut on the offside, although the under wing fixing is easy.
On my car I replaced the rear pipe with a sports one from John Worrall which is a straight through pipe without the silencer box. Heart of England no longer do exhausts but mine was one of two that he had left.
The sound is certainly nothing like a twin system but better than it was without being too noisy.
