Until you get stopped, and charged with attempting to defraud etc.
Also, just because they have a road legal stamp doesn't make them legal. They still have to comply to those standards, not just be stamped.
Coring (which is what you've done) makes them illegal.
The MoT has now been changed so that the tester can fail your bike if he believes they are excessively loud. This was done because it's too easy to get a plate or band made with the BSAU / E mark on it.
So, you've just bu&&ered some standard cans.
Best look on ebay for a new set, for when you get pulled / MoT fails etc....
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