Don't have one, never had one, don't think there's enough real estate to get one sized worth a damn in the existing midpipe because the majority of the midpipe is hugenormous resonator.

About to just shelf the car anyways. Update in my "DD Sybian" thread.

yep, you hit the nail on the head.

Have you guys put the 3 inch vibrant ultra quiet resonator to a 3 inch exhaust in an NB? I saw folks mention they were using it on 2.5 exhausts ages ago and it was tight. I was going to order that or the 'regular' vibrant one, but would prefer to go with the ultra quiet if it fits somewhere in the midpipe area....
Going to go to an exhaust shop and have a resonator and big maggie dropped in because my car sounds insane...

Oh and Vlad, my old setup with FM ish and their 2.5 exhaust with cat was pretty droney...but tolerable. There was just one spot in the rev range between 3-3.5k where it was awful inside.

Here's a link:
Ultra quiet: Regular 1: Regular 2:
Regular 3:



What do you think you're going to do Ben... once you un-give-up on the car.

Haven't had a chance to do anything much with it.

But just thought this data point was interesting.

Rattle-trap 20 year old, 180k mile hugely lifted Montero with the rear two rows of seats removed, crappy window seals, tons of exhaust leaks, and 35" mud tires at 75mph on the highway. (Under lots of load because it requires 60-70% load to maintain speed at cruise.)

Somehow this thing is quieter at speed than the Miata is at IDLE. Awesome. Ignore the 77db, that was either me messing with stereo or hitting a huge bump. Roads are awful here.

https://farm2.staticflickr.com/1809/...409611c7_c.jpg
2018-07-07_02-34-52 by concealer404, on Flickr

I believe you have a local friend that can do some exhaust wizardry.

I bought the 17950 or whatnot res. Let's see what that does. I'll download an app to check mine tomorrow, but it is awful lol.

Download the spectrum analyzer app to see what the frequency is that's being produced. For science. I don't actually know what good it will do.

It would be good for figuring out one of those j tube sound canceling things in the exhaust that vtechkiller taught me about yesterday! Basically manipulates the wave to phase cancel the noise.

That's precisely how a Helmholz resonator works.

Aka exhaust wizardry!

Will have to get new trans in the car to post screenshot at this point, but i did previously do that. Our phones (vteckiller and myself) showed a bit of a hump in the 120-140hz area. Precisely where Goodwin targets.

My buddy and I are welding in a heimholtz on my car this weekend. My car was around 120hz or so ( 3500-4500rpm ) where the drone is pretty bad. On his FD with LS7 the heimholtz totally cured his drone issues.

Mkay post results in here. I'm putting a new trans in the car tomorrow night and then will stuff the tunnels with Walmart pillows on Thursday.

yessir will do

Ok i have measurements at 70mph cruise for both of my miatas. Windows up (mostly, will explain below), stereo off, hvac off. As quiet as possible.

Subject A: 1999 w/ original motor (+5A cam), 6spd/4.30 combo, RB header, RB midpipe, RB Power Pulse muffler. (Oem hangers) K&N Typhoon intake. OEM hardtop, 56k miles, actual nice car. Full interior, everything seals nicely.
Subject B: 2000 w/ original motor (+5A cam), 6spd/4.30 combo, RB header, 949 Racing Laguna midpipe/muffler. (Poly hangers. Loud. Stupid loud. Irresponsibly loud.) K&N Typhoon intake, Junk2 throttle body. POS Treasure Coast hardtop that doesn't come close to sealing, front quarter window vents open (because i couldn't reach while driving), and the two huge "portholes" in my rear window open. Car has a.... not full interior. 106k miles, pile of junk.

Cheggit.

https://farm2.staticflickr.com/1805/...20f117c8_c.jpg
2018-07-14_01-31-53 by concealer404, on Flickr

https://farm2.staticflickr.com/1829/...c81d8872_c.jpg
2018-07-21_10-29-21 by concealer404, on Flickr

Good, right?

https://cimg2.ibsrv.net/gimg/www.mia...3e0adb44bf.jpg
https://cimg9.ibsrv.net/gimg/www.mia...26d27f5576.jpg

i had measured db levels at 84 max. But it wasn't so much the decibel level that we are concerned with. It's the frequency in hz that causes drone. My Miata was in the 110-120hz range. I did some math calculations and figured on 29" for my heimholtz . My buddy welded it for me and now the car is completely transformed. Literally where it would drone to no end 3k-4500rpm range it's completely gone . The car sounds totally different now, much more mellow hollow sound. Before it was super deep bass sounding.

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that is pretty good, does it still drone though?

I think the db numbers across different phones doesn't really mean anything, it's just relative at this point.

My concern is that the car is loud pretty much at every RPM. It's fairly bass-y everywhere.

No, it's not good. db levels are going to depend on phone mic calibration. This is bad, because the street car/dd is just as loud as the loud, and i mean OBSCENELY, IRRESPONSIBLY, STUPID AF FAM, LOUD car.

Measure the hz frequency. Weld in heimholtz, profit

Yeah i mean maybe. But realistically this needs to be 15db quieter everywhere. At least. I don't really have room for a heimholtz either, because my muffler is huge. 2-3x the volume of yours. Unfortunately if i start messing with that sort of thing, the entire exhaust needs to be changed.

I haven't measured db since we welded it in but it's significantly less. On the highway you can barely hear the exhaust. You don't have room under the car where the midpipe is for one?