Alex -
Exhaust setup on my 77 +8 is similar to yours. That is, no resonators under
the rear fenders but main mufflers in place under the doors with twin exhausts
on each side.
I changed over from the original set up, eliminating the resonators. When
doing so, a smaller diameter tail pipe from the main muffler to rear of car was
used (choice was going up or down in diameter on this rear pipe - it couldn't
be matched by the exhaust repair shop).
With this smaller rear pipe & no resonators, my exhaust noise is definitely
much quieter - reference your "smooth sounding." If you want more noise or a
"fatter" exhaust note, you might try replacing the rear pipes with larger
diameter pipes. As an experiment, try removing both rear pipes first and take
a short drive with the exhaust exiting out the rear end of the main mufflers.
This should give you some idea of the sound deadening features of the rear
pipes.
Changing the length and diameter of exhaust pipe alters not only the sound of
the exhaust but also the breathing characteristics of the motor. Racers refer
to this as "tuning" the exhaust. The changes occur because you're changing the
back pressure in the engine.
My approach is less drastic, not permanent, and free (to just trial w/o tail
pipes). I don't think I'd be punching any holes in the main mufflers.
Chas Wasser
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