the thing that dampens exhaust noise is the mid pipe, not the muffler
if you get the stock mid pipe, cut off the end, and add an original Akra muffler, it won't be loud also

Thanks for the share. Been actually browsing the net fr the answer. Some was saying about increasing back pressure

For MT07, the stock cat is not good for airflow

sos: https://www.fz07.org/thread/10460/drilling-...-stock-exhaust/


got ppl operate it and do S-flow bypass

on a 4 stroke engine, back pressure is never a good thing
it's actually very necessary on a 2 stroke engine

the U-turn manifold adds length to the secondary header
from Akra website, the U-turn system gives more power than the standard underbelly system

No engine benefits from back pressure. Even 2 strokes. But I get where you are coming from. The expansion chamber is a tuned pipe to channel exhaust pulses to the combustion charge from flowing out too easily, the opposite of scavenging for a 4 stroke.

But its easy to make the mistake putting on a too free flowing exhaust and sacrificing exhaust velocity. Which is why the S/U midpipes are there for, the longer running length exhaust promotes or maintains exhaust velocity.

Symptoms of a reduction in exhaust velocity is poorer scavenging leading to less efficient burn and a possible noticeable drop in engine response and torque.

Just know that exhaust systems diameter, design and lenghts are "tuned" by the manufacturer to give a particular powerband. Changing such will also change the powerband and may run afoul of the stock tuning.

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This post has been edited by alexei: Aug 15 2025, 02:55 PM

Yes. That.


Euro 5 and 6 to blame. Which is also why the NK's stock exhaust sound is so good. They probably DGAF on EU noise regulations.