Hey everyone I wanted to share a little bit of my experience when I when down a customized stock exhaust route so perhaps others can learn from my successes and failures. To preface this, I initially wanted 'slightly' more aggressive exhaust sound than stock so I'll try to outline my journey here as well as my impressions of each configuration.
1) Stock mufflers, stock center resonator with baby resonators deleted:
I first started the quest by installing non-resonated downpipes on an otherwise stock system. Nice results, a little more aggressive but still quite mellow overall and no drone. Eventually time passed and I determined I wanted more sound.
2) Stock mufflers, center resonator delete, baby resonator delete:
I then deleted the center (large) resonator and had 2 straight pipes installed in it's place. This sounded horrible. Terrible rasp and drone to the point where I didn't even want to accelerate because of how awful the car sounded. This was remedied in a hurry.
3) Stock mufflers, all stock resonators deleted, Magnaflow resonated x-pipe added by downpipes:
This was much better and sounded just slightly more aggressive than my setup in step 1. No drone or rasp at all, but a little quieter than I ultimately wanted.
4) Muffler delete, Magnaflow resonated x-pipe
This setup had a pretty nice sound (IMO) under throttle and wasn't obnoxiously loud, though definitely louder than setup 1 and 3. The rasp was gone. However, it had some wicked drone from ~1700 - 2500 RPM. I added some sound dampening material to the trunk, spare tire well, and behind the back seat which helped a little but wasn't enough.
5) Magnaflow resonated x-pipe, dual Vibrant bottle resonators
I had hoped the bottle resonators would absorb some of the resonance but they really didn't do anything at all to help with that. They quieted the car slightly but the overall impact was pretty minimal and I still had more drone than desired.
6) Magnaflow resonated x-pipe, dual Vibrant bottle resonators, dual J-pipes (branch resonators)
I finally bit the bullet and decided to try branch resonators. I had these welded into the downpipes and run back parallel to the exhaust until they met the center brace with the goal being to try to get in the 34-35" length range based on calculations of drone frequency and sound wavelengths). They ended up being about 32" because we ran out of room due to the cross-brace but I thought that might be enough. These made a huge difference when the car was cold. There was absolutely no drone whatsoever. However, when it heated up, I was still getting more drone than I wanted because the exhaust gases heated up and the wavelengths got longer, hence the need for the resonators to be a little longer than they were.
6) Magnaflow resonated x-pipe, Magnaflow non-resonated x-pipe, dual J-pipes, dual Vibrant bottle resonators
I wondered if a second x-pipe would help to curb some of the resonance if added further back in the system so I had one of the non-resonated pipes put back in the area where the original factory large resonator was (so the straight pipes were replaced by the x). This provided a negligible improvement as well, on par with the addition of the bottle resonators.
7) Dual Magnaflow resonated x-pipes,dual J-pipes, dual Vibrant bottle resonators
I found a shop that could manage to squeeze a second resonated x-pipe in where I first had the non-resonated X installed (the location of the factory center resonator). This made a big difference in the overall sound level and did help somewhat with the drone but still didn't eliminate it. I have added some insulation to various areas in the trunk and that has helped as well. Overall the drone is pretty manageable and not evident at cruising speeds unless I encounter a gradual hill where a partial-throttle scenario occurs in the 1800-2200 RPM range.
You might be reading and thinking that I'm an idiot for trying so many things with stock system as a base and you're entitled to your opinion. Why did I keep trying to make the customized system work? Initially a 'relatively' small cost to have a shop weld in a couple new parts or cut out a couple old parts. I'm thinking I can drop a couple hundred bucks and it should get me close. As time goes on and I've tried more and more it becomes the argument of trying to fix what you now have more invested in or cutting bait and getting a fully engineered system. This coupled with the fact that it seems not even all the aftermarket solutions are drone-free so. Finally, my own curiosity as an engineer lead me to really want to try some different things to see how impactful they really were.
At the end of the day, I'm pretty happy with the sound now and I learned a few things along the way. All in, I have around $1100 in parts and labor for all these iterations. If I had just skipped right to the system I describe in step 7, I would have been at somewhere around $600 parts and labor. I wanted to post this just to give some details and observations on my own experience so people who are considering this route can perhaps either skip some of the intermediate steps that I took or say screw it and pick up a true aftermarket system if they don't want to deal with the hassle. In the attached image, you can see the dual resonated x-pipes and the branch resonators. The bottle resonators are back where the stock mufflers used to be.
Cheers!
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This will assist me in future when I plan on dabbling in such things after my warranty is up. 
Originally Posted by Envy187
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