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-   -   3inch exhaust too loud? (https://www.miataturbo.net/general-miata-chat-9/3inch-exhaust-too-loud-11228/)

Braineack 07-17-2007 12:52 PM

I'm sold. I'm going to copy whenever I redo mine...I always knew if you chose components wisely you could achieve it. but his is no louder than mine (but sounds better) and mine is as loud as stock.

TurboTim 07-17-2007 12:58 PM


Originally Posted by y8s (Post 132077)
It's almost too long and I'd use this one if I did it again.
Matt

That 5x8x18 is the one I used. Ther's also "non-polished" versions that are a little less money that I didn't know about until after I installed my shiny one. You can't see it anyways.

Mine is (2) 2.25's into 3", metal core cat (Vibrant), to that muffler. No resonator. No drones ever even without a resonator. You can make a pretty straight exhaust with that magnaflow muffler. I've been redoing mine for around $450 though (similar to Enthuza's 3", but straighter and lighter).

I WILL get a sound clip of my exhaust soon damnit. Mine is louder than stock but still quiet. The intake/turbo/sucking noise is much louder than the exhaust.

y8s 07-17-2007 02:06 PM

you guys keep talking about this intake sucking noise. I think you're all just trying to fu*k with me.

Braineack 07-17-2007 02:22 PM

no way dude....mine's loud as shit...

http://www.youtube.com/watch?v=IxSSi80Lv8s

cant even hear my exhaust over it.

y8s 07-17-2007 02:48 PM

Didn't hear that shit on my car did you? :D

Braineack 07-17-2007 03:23 PM

nope

cueball1 07-18-2007 02:12 AM

Is the intake noise (and it is noise, it ain't pleasant) from air movement or is it the open access to the turbo spooling? I've always figured it's the sound of the guts of the turbo resonating out the intake pipe. I've never had an open intake on a non-turbo car. Anyone know?

Slidin'Miata916 07-18-2007 02:49 AM

Whats with the smoke? Great run, And even greater power on the dyno.

wildfire0310 07-18-2007 03:12 AM


Originally Posted by cueball1 (Post 132294)
Is the intake noise (and it is noise, it ain't pleasant) from air movement or is it the open access to the turbo spooling? I've always figured it's the sound of the guts of the turbo resonating out the intake pipe. I've never had an open intake on a non-turbo car. Anyone know?


One of the noises you hear is just the sound of the air been sucked in, cause even on my N/a with open filter you can hear my intake above 4g. nothing compared to that of a turbo's whistle.



2-1/4 turbine outlet expanding to 3"
3" cat in stock location, soon to upgrade to metal cat
3" dynomax 12" bullet race muffler (perf, not louvered) in resonator location
3" magnaflow 22" perf core muffler. It's almost too long and I'd use this one if I did it again.
3.5" Gibson stainless steel tip, cut shorter so it doesn't cut up your shins.

Thank you, I looked that photos, but that lays it out greatly, and should be a great help to all the future members.

y8s 07-18-2007 10:20 AM


Originally Posted by cueball1 (Post 132294)
Is the intake noise (and it is noise, it ain't pleasant) from air movement or is it the open access to the turbo spooling? I've always figured it's the sound of the guts of the turbo resonating out the intake pipe. I've never had an open intake on a non-turbo car. Anyone know?

air makes noise when it has to do anything other than flow smoothly.

in most turbo miatas, the intake of the turbo is TINY and has sharp corners (not the piping, the actual turbo inlet). in mine, there's a 4" turbo inlet that's got a nice big flare on it. And a 4" pipe. Check it:

http://gallery.y8s.com/d/433-3/gt25_86ar_01.jpg

Also, I previously had the filter mounted directly to the turbo and there was still no SHHHHHHHHHHHHHHHHHHHHHHHHHHH sucking noise.

Next time you're at Best Buy, check out the mid-hi end speakers with ports. You'll see they do the same thing for the same reason. It keeps flow velocity at the edges of the pipes closer to zero in an ideal case. less flow velocity, less noise.

The math is complicated but compare the volume flow rate of a 1 m^2 opening at 100 m/s and a 100 m^2 opening at 1 m/sec. Both give you 100 m^3/sec volume flow rate. The "trumpet" shape basically trades velocity for area. as it expands, area increases to infinity while velocity decreases to zero.

You can buy these doo-dads for your kit too...

mazda/nissan 07-19-2007 01:09 AM

who's complaining about intake noise? thats what gives my 240 any balls at all due to the chopped air box (sounds saweet though)

Savington 07-19-2007 02:33 AM

Back on topic, my 3" Enthuza is barely louder than stock. I really like the note.

speedf50 07-19-2007 05:05 AM

So, are people running 3" cats and cat backs on 2.5" DP's? I ordered the FM kit and it comes with a 2.5" DP if I am correct, is it still ok to run 3"? Or do you guys run some kind of 2.5 to 3" cat or adapter?

And are there any clips of a 3" with just a muffler and no resonator? I like my car to be slightly obnoxious:D. Any clips of 3" no mufflers?


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