Been reading about people de-restricting their standard exhausts, with a fair few cutting them open to find nothing inside to restrict, so I thought I'd put this info I came across this week, to help those thinking of doing theirs.
All pre 1999 standard exhausts have the 3MB code stamped on them,
the only restrictions these exhausts have are a 'cone' that is tack welded at the engine manifold end, easily taken off with a dremel or similar to break the tack welds, these DO NOT need to be opened up, to de-restrict them.
All standard exhausts made after 1999 have the code 3RM stamped on them,these exhausts DO need to be cut open, are restricted by a 'ring' inside the expansion chamber, same as in the picture below.
Hope this helps people in the future, as they can be a pig to weld up at the best of times, hopefully this will stop people needlessly cutting theirs open.
