400E exhaust modification??
 

When I was in local car auction today, I noticed a 1990 300E had the same exhaust as my 400E, you know, that kind of 2 hole muffler. I wonder if all 300Es and 400Es use the same kind of catalytic converter and muffler. Giving the fact 400Es have 90 more horse power, I would be surprised if their exhaust systems are the same.

Since it's quite difficult to modify M119 engine, can I get 10-20 horse power increase by just replacing the stock catalytic converter and muffler with some high flow ones?