well i put it up on a lift at work today and looked at it and unless i dump it i wont have room to have the tailpipes exit in front of the rear wheel because my muffler is set too far back. i am going to get supplies for adjustable side branch resonators and attempt that next week. good point on adjusting each bank seperatly. i'm assuming that the left tailpipe branch will need to be longer since it is longer than the right? from what i read it looks like i will need around 32" give or take a couple. i have plenty of room so i am going to just run them on top of the muffler. wish me luck!!!

 

I'd make them adjustable between 30" and 36" at a minimum if you have that much room. The calculated length to cancel 1500 rpm drone is 36", 1800 rpm is 30". My drone was occuring around 1600-1700 rpm with the Magnaflow single exhaust. I started mine out at 30" and it worked good except for a little bit of a drone when I started it up cold and it was idling fast. Other than that, the drone was gone. A couple weeks ago, I rerouted the resonator so I could get it to 34"-35" and it helped with the fast cold idle drone.
The speed of sound does get faster and the wavelength of a given frequency longer as the exhaust gets hotter. Enough so that the wavelength change makes a 3 or 4" difference in calculated ideal resonator length from cold to hot (hotter = faster = longer).
Good luck and be sure to post your results. Hope this helps more people get to understand drone and why it happens. There's a formula out there that will explain the behavior of almost everything. The hard part usually is finding that formula.

 

well last week i went to my exhaust guy with a picture i drew that showed him how i wanted to make the branch resonators. he said that he has had alot of luck in the past putting a h pipe in after the muffler that sticks into the existing tailpipe at a 45 degree angle to create some turbulence. well today i took it over to him and he put one in before the muffler and after the muffler and it helped big time! it still has a slight drone around 1500 rpms but its way better than it was before! the weird thing is that the h pipes seemed to quiet down the exhaust some. in any event, for the meantime i am going to keep this setup until i get bored with it and decide to do a full exhaust with longtube headers. thanks a ton for the info murphdog!

 

honda uses this set-up on their S2000s from the factory

 

Here is a pic and Videos of my fix for Exhaust drone, my system is SLP Headers, 2.5 inch duals, Random Tech Race Cats (100cpi), Magnaflow X-Pipe, 2 each Magnaflow Bullets and 2 each Magnaflow 14 in oval mufflers all strait thru design out the back. It works great no drone except at Idle and sounds good.
Startup and Idle:
(http://www.youtube.com/watch?v=A9SWc0Sx1Lo)

Startup and rev:
(http://www.youtube.com/watch?v=QDkuqRRXVUA)

 

Did this on my truck helped out alot but if I were to do it again Id make it adjustable so I wouldn't have to cut and weld it over and over.

 

Nice idea...

 

I have an odd situation with my exhaust. basically we have a system with 4 cats, then a resonator, then the muffler right at the back with the tips coming off of it. I had the muffler removed by an idiotic shop (I should be slapped) and what he did was run pipe from the resonator to the drivers side tip, then just cut a hole in that pipe and branched over for the RH tip at near a 90* angle!!

the RH tip whistles as well as having a drone in the cab at 1800-2200. I want to install a resonation cancel chamber but not real sure where it would work best at. The length between the resonator and tips is only about 3ft.

The engine revs to 7000 and there is no drone at idle, only slightly above cruise rpm so everytime you bring it on the pipe at all, it hurts...

 

Sounds like he butchered it up. If you kept that system I would move the muffler up, and run the chamber after the muffler. If it were me I would make a new exhaust. Why do you have 4 cats?

 

OK, I just had the exhaust reworked with a true Y. It moved the resonance from 1800 to about 2200 but still SUPER annoying and wife will never accept it. I will try to post a pic here but basically at the back of the ride, around the rear wheels, there is the resonator, comes out of it about 2 ft, then Ys out 2ft each side to the dual tips.

I really need to grab the math behind this problem so I know how to fix it. I did see that calculator at autolounge but that does not tell me much other than frequency wave length. The cross tube we are talking about here is actually a negative wave attenuator that reflects the resonant frequency at an opposite sine to cancel the wave? Or is this based on another principle?