where shall I put it, I did forget to mention that I have a single into duel flowmaster

 

off the side of each pipe?

 

That'll work. You can probably get away with using a smaller diameter pipe if you are running duals.

 

 

This WORKS!!!! I did it on my 01 turbo truck with single 4" off the turbo split into duel 3" tail pipes and duel Mangnaflow offset, strait though mufflers. Droned BAD at highway speed, 65-75mph. So I built these. The first ones where about 22" and still had some drone, so extended them to 32" and NO DRONE!!! So much nicer!



So last week, I put the new MBRP 4" down pipe back exhaust on my DuraMax with an Edelbrock strait though diesel muffler on it and damned if I didn't have a bunch of drone with it to at 62-75mph! Since I have 7K miles to drive this month, I thought I'd give this a try again. Made the same 32" long 2 1/2" tube resignation tube like on my gas truck and welded it on the tail pipe after the muffler and it KILLED all the drone again!! The truck is barley louder then with the stock cat and muffler. 32" seem to be the magic number at least for an ECSB. So this work on both gas and diesels.

 

Impressive! Good job!

 

Just to help out, if anybody cares:

VERY simplified formula:

1100ft/sec (speed of sound) divided by drone frequency = full wave length.
Full wave length divided by 4 = quarter wave length.
Quarter wave length multiplied by 12 = length in inches of the Helmholtz chamber required to deal with your particular drone frequency.

 

Glad to see you guys having success with it

 

Does it matter on the diameter of the pipe used?

 

old thread but I am sure people could benefit from this.