Have you ever tried this? Seems like they are usually placed after the muffler but I don't have room after.
Yeah I'm currently running one right now, but this one is short. It doesn't seem to make a crap bit of difference to cut down on tone/volume/resonance, but again it is short. I'm sure if you can a 12" resonator it would 'work'! I do not see a reason why you could not run the resonator before the muffler, aside from it changing the sound of the engine before it hits the muffler (you really wont notice a difference).
Judging by your pic, you should be able to use two 12" resonators before the y-pipe.
Not too sure what exactly you're going for in the exhaust setup but a couple things I have figured out with exhaust on our trucks:
-Combating noise is a PITA compared to American vehicles, damn ricer

-More bends reduce noise volume (cut flow, but its worth the trade off with an angry bumble bee under the hood)
-More tubing = somewhat less noise
-More muffler &/or More baffles = less rice
Good luck man. let us know what you come up with!
Can someone explain to me why you want the exhaust to exit before the rear tire? Is it an off-road thing?

I don't believe there is a performance gain and no matter the muffler, I think the sound is going to be obnoxious when the muffler is too close to the exhaust tip. I recall driving up to Tahoe next too Jeeps heading to the Rubicon trail with exhausts exiting before the rear tire and just thinking "Damn that sounds like Sh!t" and they are gonna have serious headaches once they get there.
Now, I'm not hatin' just curious. So holster the flame throwers.
Its easier to build the first go round, trust me. The noise is... Impressive at that. Especially passing or overtaking another vehicle. They just look at you with their jaws on the ground! :laugh: