Don't get me wrong, I like the MRT V2 for my V6, for the most part. It's just the low rpm and highway drone that I feel is going to get to me and make me remove/sell it down the road. Currently, I am in the process of using sound dampening mats (10 mil FatMat) and foam (ensolite) to cover my inner trunk and under my back seats, hoping that will get rid of the in-cabin resonance during the drone. I don't mind the sound of the exhaust, it's the resonating vibration inside the car I'm trying to deaden during that rpm range that it happens at. I've gone through a lot of threads, covering different possibilities (resonated x-pipe, resonator delete, sound dampening mats, etc) but can't find a definite answer as to what absolutely works. So if this doesn't help, has anyone figured something else out?
And please stay on topic. I don't need anyone saying I should've gotten a corsa, solo, flowmaster, etc. Thats not helping my situation. I know what's out there and I went with MRT. I can't just remove it and pay hundreds of dollars for something else. At least not right now. And I don't mean for this to sound rude, but if you haven't done it, don't suggest it. I can't afford any trial and error possibilities. So if you're gonna tell me to TRY something, I'm not going to do it unless you've done it yourself and/or know that it works because, if it doesn't, I've wasted my time and money.......and will hate you forever :-)
**UPDATE** 11/29/11
So, the Helmholtz pipe works and it will work for pretty much any exhaust with the right calculations. Mach's calculations for the MRT seem to be spot on. I have 0 drone now as well! Even at low speeds, theres no annoying vibrations and i no longer have to get out of that drone rpm range. We both have a Vmax ported throttle body and Vararam intake (which made it easy for me to just copy his measurements). We don't know if that's a factor in the equation but would recommend you make your own calculations and get your own numbers to see what length of pipe to use. It absolutely does work though and I completely agree that this is now the perfect exhaust. It's quiet when I want to drive normally and still has sound when I want it. This should work for any exhaust with the right length of pipe.
"Anytime the drone hits around 120 HZ it should be canceled out by the helmholz principle. I had my app running while shifting through gears and the 120 drone comes up every time as I accelerated. The pipes will only cancel out your target frequency and +-400rpm from the target. So it should pretty much take care of the drone. For 120HZ cancellation the Pipe needs to be around 29 inches when measured in the middle of the pipe.
I suggest running the SigScope app and getting your drone HZ. Because I have a vararam intake and a vmax TB so my drone maybe vary slightly. Heres the formula.
Basically take 1100 (speed of sound) and divide that by your drone in HZ
Then divide by 4. Then multiply by 12.
1100 ft/sec divided by 127.7 cycles/second = 8.6139 ft/cycle (cycle being 1 complete wave length).
8.6139 ft/cycle divided by 4 = 2.1535 ft/ quarter cycle (or quarter wavelength).
2.1535 ft/ quarter cycle X 12 inches/ foot = 25.84 inches"
-Mach