concealer404

iTrader: (3)

No, there's a PPF and driveshaft there. And a huge resonator that takes up the majority of the midpipe.

andyfloyd

You dont need the PPF and driveshaft. Toss those

sixshooter

iTrader: (12)

Have you tried a banana in your tailpipe? Seems like the best option.

huesmann

iTrader: (1)

Just knocking down the noise in one frequency range isn't helpful—at least not in a street car.

Concealer, have you had anyone else do a ridealong in your car? Like maybe your ears are particularly susceptible to the combo of dBs and frequencies produced by your exhaust? Although, I guess finding out someone else doesn't think your car is annoyingly loud doesn't really help you.

I'm dealing with a noisy muffler of my own. Have you noticed the level of annoyance changing at all with drive time, i.e. bearable from a cold start to a few minutes of drive time, but then it starts getting annoying?

ridethecliche

iTrader: (2)

Which resonator were you running again? Vibrant Ultra Quiet?

concealer404

iTrader: (3)

Yes, have had a few people in it. They all think it's loud.

No change, it's just always loud. It's not horrible at warm idle, but it's still not great.

I'm sure there's some frequency stuff going on here, it's very bass-y and droney. But on the other hand, regardless of HOW it's doing it, it's as loud on the highway inside as the rattletrap track build with the world's loudest exhaust.

andyfloyd

How is it not helpful? My car would give me a headache before because there was so much drone in the 3k-4.5k rpm range. Now with literally a 28" pipe welded in there is ZERO drone in that same rpm range. My car is a "street car". So how is it not helpful, Im curious....

concealer404

iTrader: (3)

It's helpful, but only in that range. This is painful from 1200-7500rpm.

andyfloyd

fair enough. Really the only drone I get anymore is right off idle around 1500-2000rpm. After that its pretty quiet though the whole range.

huesmann

iTrader: (1)

Having someone sit in your car and tell you it's not annoying loud to them isn't helpful to you, when you're the one who has to live with it. Capisce?

Concealer, do you have access to a stock exhaust, for comparison's sake?

andyfloyd

lol, ok well I was just giving him ideas trying to help since I just took my exhaust from droning headache inducing to nice and mellow with a heimholtz. A stock exhaust literally makes no noise whatsoever. I think Concealer knows what a stock exhaust sounds like. Capiche

concealer404

iTrader: (3)

Not really. I have the OEM muffler section from my other car in the shed somewhere, but i seem to remember removing it with a sawzall so i'm not sure i could install it on something else. I will be able to take measurement of a stock car with a soft top at same speeds sometime next week at MATG though.

huesmann

iTrader: (1)

Ah, I get it. Your exhaust sounds good to you—even though it's probably louder than Concealer's—because you're deaf!

Aren't the NB exhausts 2-piece? Bolts at the axle flange were seized?

sixshooter

iTrader: (12)

Is the interior intact? Did you remove the padding beneath the carpet? Perhaps it has something to do with the resonance of your echo chamber? Putting some Frost King up under the package shelf carpet really helped mine.

Your car may still be too loud but sometimes reducing the resonance within the cabin can help significantly. The string makes very little noise without the resonant body of the acoustic guitar.

andyfloyd

WHAT? Say that again I cant hear you...

Im sure my exhaust is still louder than his is, I hit 83db or so under WOT, it just doesnt drone anymore which was the major issue with mine. Sounds to me like concealer needs to make a custom exshaust with a totally different muffler that will be quieter.

concealer404

iTrader: (3)

Probably. Or maybe i was just playing with a sawzall? I'll look at it later this week.

Interior is intact. Carpet padding is present. I have some mass loading stuff, i'll try to find time this weekend to mess with some of the stuff i was going to do anyways.

vintagerust

Hey Concealer,

When I had an NB2 header, stock midpipe with dead cat, and a Magnaflow "muffler shop special" that came with the car for the axleback, it droned. I then got an RB header. Still droned.
Poly diff bushings and a lightweight flywheel sure as hell didn't help either. lol
I was probably getting more gear-whine/flywheel noise than exhaust noise from that setup. But I did get a decent spectrum analyzer app and I took some logs. 127hz was my loudest freq. at cruise.

I just picked up a Cobalt midpipe with cat and resonator, since my cat was dead, and I paired that with a Goodwin Racing RS4 w/ helmholtz. I need to take a db reading, but with the baffle in, it's very civil. Even with the baffle out, the car is quieter past 70 than my old setup. When I looked at the spectrum analyzer, I noticed that once you let off, or cruise along, the peak at 127hz falls, and you get a lower volume plateau in the lower freq range (80-150hz). Granted, that doesn't mean this exhaust is silent. It makes more noise under accel, and that's just going to happen when you step up in exhaust diameter. The difference, is you can settle into a cruise, and it just quiets down. There's still a little bit of a boom in the 55-70mph range, but it actually quiets down once you get past 4k, so highway trips at 4300 rpms shouldn't be too bad. Especially with the baffle in. Then when you want to rip and hit the track, you can uncork it, and let it sing. And if you want to knock it down just that extra bit, I think GWR sells a packed baffle, as well.

Andy's setup isn't bad looking either. I almost built something of a similar design, but with a chamber, instead of a branch. Branch resonators tend to have a narrower range than a chamber more akin to a "bottle" with a neck. But with his design, you get the added resonator to further damper the sound. Plus, he's also tested it to work. lol

But ultimately, it's a Miata. The window seals aren't great. Wind and tire noise is still a large contributing factor to the cacophony of noise at highway speeds. You're just not going to have a quiet, luxury car experience, no matter how much you quiet the exhaust. That's better suited for a Volvo C70, Mercedes SL, etc.

I'll try and get back to here with a db number the next time I go for a drive.

Oh! And make sure your exhaust isn't hitting the heat shields. I had noticed my midpipe was SUPER close to one of the bolts on the heat shield in the trans tunnel. Just kinda beat that out of the way an extra mm or 2 for added clearance. And the shield under the rear muffler may be rattling like hell with your engine mounts. May want to check that out too.

concealer404

iTrader: (3)

Hey thanks dude.

Any chance i could trouble you for a good quality video of what it sounds like? What i struggle with is that the full RB setup sounds AWESOME, and any video i've seen of the RS4 so far is either on a completely stock car otherwise, or sounds like wet farts. I'm hoping most of the wet fart noise is from people taking crappy videos, which may be a losing battle. Even my own video of the RB setup isn't really accurate-sounding, it's way less raspy in person.

I can't actually hear any wind or tire noise over the drone at the moment, so the goal at this point is to get the exhaust quiet enough that i CAN hear some wind noise.

I don't mind some noise during acceleration, i even welcome that. If i wanted it to be completely silent i would have sourced a stock exhaust, but i wanted it to sound cool and be fun. The car is close to perfect, it's just this and that damn vibration at speed i still can't figure out.

vintagerust

Ignore my ramblings. Skip to 1:45 for startup and revs. It's not very long.

concealer404

iTrader: (3)

Hah i actually ran across that video yesterday. Is it just the video? It sounds pretty raspy, i had it under the "wet fart" category, but it may not be like that IRL.

For comparison, here's the car in question:


There's absolutely no hint of rasp in person.