Exhaust design is al about getting rid of the exhaust gasses as efficient as possible. It all depends on engine displacemnent and rpm. In other words the actual gas volume going through the exhaust.
From rather long experience I know that brass instruments (yes I'm also a trumpet player) work slightly different [8)]
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<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</i></font id="blue"></center>