No. They are still exactly the same design as they were. You can see evidence of uneven gas pressure and temperature distribution in most MM systems fiitted to XTs for any length of time, as they have significantly different discolouration on the rhs (shorter header), when compared to the left.

But to give MM some credit they were never sold as "performance" systems, they were/are marketed to aid ground clearance and reduce weight (which they do very well).

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