The little can looking one is a helmholtz resonator. It does the same thing, just more complicated to make from what I've read.
If you have true duals [ no H or X pipe] you would need to start by multiplying 2 to the rpm that droning occurs because each bank of your engine only fires two times per rev. Then make two identical resonators.
Since mine has a X-pipe the math worked the same as single exhaust, I just needed to build two resonators.

 

Very interesting. I had a Magnaflow 14" SIDO installed; Duals (rear exit) and we eliminated factory Resonator. Sound is great, except of course for the drone @1700-1900. I've read in other places that adding a round straight through muffler like the Dynomax Bullet will eliminate drone.

Anyone have experience with this method?

Thanks

 

Pics? would be awesome. What size pipe did you use for the resonator. And do you think it would matter at what angle this reonator meets the exhaust pipe?

 

I will try to get under my truck and get some pics today.
As far as pipe size goes, the closer you can stay to the exhaust pipe size the better. However I have heard some guys say they are getting pretty good results from pipe as small as 1 1/2".
The resonator has to meet the exhaust pipe at a right angle [90 degrees] for it to work properly, but can have bends anywhere else in it's length.

 

[IMG][/IMG]
here is a rough diagram of a branch resonator. Don't have any pics of mine yet because I don't have a camera with a flash. I'll get one on soon.

 

So, This is my thinking:

My drone bugs me at 1700-2200, take the average and the rpm i get is 1950.

1950 rpm x 4 = 7800

7800 / 60 = 130

1259 / 130 = 9.68

9.68 / 4 = 2.42' which is rougly 2'-5".

I have 3" piping and then a splitter to 2.5" tails, What size of pipe would I use? EDIT just read post above. If my logic sounds right, a 3" pipe would absorve more drone, correct?


If I can get this to work, I will definitely jump aboard on the aftermarket cat wagon and see what the maggie-pack does at higher rpms with rasp and pop, kinda like it when it opens and decels too.If anyone can recall 08fx4's exhaust on his ol' white truck thats what made me go for this muffler I have now.

 

Looks right. I installed mine after the mufflers which is where most of what I've read recommends. I'm assuming you have a SISO muffler with the y after the muffler. If thats right than one 3" resonator would work.
Also I think you should pick the rpm the drone is worst not just the average. For example my exhaust had drone between 1700 and 2000 rpm but the loudest was at 1750 so thats the rpm I used to calculated my resonator. A lot of people build the resonators so that they are adjustable using a slighter larger or smaller pipe inside or outside another. It can be slid in or out like a trombone to fine tune the length. I didn't have room for this but it may be a option for you.

 

I believe these guys at Solo are actually doing a form of it on their MR400 single system for the V8, they call it a J-Pipe:http://solo-performance.com/ford-f15...exhaust-system See pics to the right at web sight.

Great info though on eliminating drone. Something we probably should be doing when it is an issue which is quite often.
O and their J-Pipe is adjustable which is a great idea, so you guys could make yours to adjust (slide in and out) that way you can tweak it and also use it with different mufflers if you want a change. Just my two cents about it.

 

You assumed correct. What I'll have to do is run around with the stereo off to see where it really is that bugs me. Its normally between 60-65mph but I cant recall what my engine is spinning at (rpm).

Thanks!!

 

I have a single in, single out 3.5 diamond eye catback on my 2014 f150 5.0 and the 1750rpm drone is horrible. Are you installing the J pipe in front or behind the muffler ? solo J pipe is infront of muffler