13B Extend Port exhaust question - help needed

[RX MIDGET]

Hi,
I hope someone can assist me with an exhaust question I have relating to my 13B Extend Port fitted in an MG Midget.

On purchase it has 2 small "hot dog" size mufflers, (one small on close to headers and a larger one half way along the car).
This leads up to a larger muffler that has both entry and exit from the same end of the can. Never seen this before, I was informed it was required due to fitting placement on the modified car, and was required during the re-Engineering process under our local laws for noise reduction.
Trouble is, it muffles the sweet rotary noise unless giving the car a boot full of throttle. Exhaust diameter is 2". Engine is Non Turbo.

My question:
If I removed / reduced the size of the larger muffler, (obviously the car would be louder than the 88DB @4500rpm) but would there be any issues with:

1. Engine damage through lesser back pressure, or,
2. Performance reduction
As I am newish to rotaries, I do not wish to learn from guessing!