Yea, a helmholtz resonator...interesting thought...

 

I was amazed at how much my 4" borla XR1 toned down my corsa. Granted the corsa is basically one giant helmholtz type design and is all rasp, while the packed XR1 takes down rasp... its almost like they work noise from opposite ends of the spectrum. Whatever the reason its quiet for a straight through design 4" exhaust on a gasser.

 

Magnaflow makes some of the better sounding mufflers IMO. Get one with a built in X pipe or straight through. I had a 22" one with built in X pipe on the previous engine in the S10 and it sounded great. I now have a 18" on the Silverado and it's fairly loud. The 14" ones on the GTO were really loud. For quiet and performance of just go one large 22-28" 5x11 magnaflow.

 

I'm going for something TIM Z did to his exhaust. He's running 2 magnaflows. I just got my second one in. I'll be running a 14" 14151 and a 22" 12909. Hopefully my truck sounds something like his. Here's the thread with video clips he made.

https://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/new-exhaust-some-info-539934/

 

Seriouly dude, they work! I've done 5 of them. First one on my truck was when I had the blower on it, and at the 1800-2300rpm range, dropped 10dB in the cab according to the app on my phone. On my druamax, completely killed all the drone of the 4" strait through exhaust on it.

 

Its not so much a drone as more just an annoying rasp. Just like a 350 with straight pipes, super redneck sounding lol

Going to the track tomorrow if it doesnt rain! I am only going to take 2 slicks instead of all 4, I think I can make that stick. Should help the mph running in 2wd as well.

 

Very curious to see what you run

Too bad you never ran the turbo all out in the quarter

 

No doubt the Helmholtz resonators have their merit however they do not change the sound characteristics such as Richard has complaint with. I added the 'j-tube' to my 4" setup which reduced the droan in the cab at the tuned frequency but did not affect the part throttle 2K rpm rasp what so ever. My proposed resolution is to change the exhaust to a true dual setup with an x-pipe followed by two 5x11x22 Magnaflows with a side exit. I would really like to do a symmetrical dual setup but requires relocating the fuel tank to a cell in the spare tire location first.

 

Are you turbo or blower and how long of a j tube did you add? I'll be adding a jtube to my exhaust tomorrow. I've got a 3" dp, then immediately goes 4" mandrel pipe (squished about 1/2" to clear first crossmember) to magnaflow 12772 4" 30" long muffler then 4" mandrel tailpipe. Pretty quiet but a bit too bassy and droney as hell 65-75mph, like ear piercing drone. Atomic sorry to thread jack!

 

Blower. I started with a 32" and it seemed to attenuate the 1800-2200 rpm range. I later shorted it to 28" and moved the attenuation up to the 2000-2400 rpm range. I would like to move it up to 2500 rpm for interstate cruising which I calculate to be ~23".