got this reponse, not detailed but ......
EDIT:
After some more research today, I am leaning towards installing some summit glasspacks just as Mopar73340 has done in his location next to the gas tank. What I am finding is that these resonators available today are simply small glasspacks anyway, but with a bigger price tag.
thanks everyone for your input. Ill post my before and after results in this thread. Going to try to get it done next week.
EDIT EDIT:
I measured the existing tail pipes about where I could just cut the tubes and slap in a couple of glasspacks and muffler clamps and be off and running......
not enough length to use current pipes/bracketry. Would have to redo the pipes from the mufflers back, so this project is going on the backburner.
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Thank you for your inquiry for Dynomax Exhaust. We appreciate your
interest in our products. In regards to your 1970 Dodge Challenger 440,
yes, if you use either our race bullet or our glasspack as an in-line, it
will help and reduce the resonance on the inside of the vehicle.
If you have any further questions, please feel free to contact our tech
line at the number below.
Thank You,
Terry D
Dynomax Performance Exhaust
Installation Technician
Tech Line Number For a Dynomax Dealer Near You
1-734-384-7806 1-734-384-7807