The AMT pipe on the ZDZ80 single is a wild combo - mine turns over 7000 on 26x10 mejzlic.
This pipe is good on the single 80 - with rpms setup to be in higher 6000range and low 7000 range .
For most applications tho -go with a 80mmx300 JMB can on extremely short header - 5-6" long for best power .
still the best power to low sound & lightweight setup going. expect mid to upper 6000rpm range on Mejzlic 26x10 -
like any of these engines -- best power is in upper 6000- to low 7000rpm range
the noise tho -especially on in cowl "mufflers?" becomes pretty awful.