A big can on a very short header just makes for a nice muffler - non restrictive -
a couple of hundred over an in cowl setup is reasonable -
I use the full length KS tuned pipes on everything from the 50 single-to the 160 ZDZ .
They do get long ---
the over 70 cm to tuning point is pretty common .
pretty much the same setup on the DA150's . The power boost is really excellent and smoooth transitions.
So far the quiet muffler by JMB - with very short headers is about the most fool proof setup I have tried.
No "boost" but much better than the in cowl stuff.
best setup for 3D where you are just "throttling"all the time