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Muffler recommendations


turbogrill
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Hi,

 

My Miata is too loud according to my local track so I need a different muffler.

 

I currently have the Good Win Racing Race muffler. It's supposed to be around 85db on a stock car, and I am running stock (hehe yeah right).

 

Any recommendations? I remember there was a thread about this, but can't find it.

 

Obvously I can not afford to loose any HP.

 

 

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I have always had luck with the Vibrant mufflers.  I've got one on my street car, and it's liveable, (turbo helps a lot).  The race car is getting one of their 3" resonators, and one of their mufflers.  Hopefully that'll be enough to make a VQ liveable sounding.

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After destroying a half dozen of so mufflers with a rotary I finally bit the bullet and installed a Racing Beat muffler. You can use them on a piston engine just as well and they should last forever, the case and perf core are thick stainless, and the packing is stainless wool instead of glass. In the long run they shouldn’t be too much more expensive than conventional mufflers.

 

IMG_20151212_103724.thumb.jpg.45f398fcb977a677eced7ead387259fd.jpg

 

IMG_20151212_103719.thumb.jpg.243226388cc6ec3dc4e5b8701e3bf738.jpg

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On 8/30/2019 at 7:54 PM, Burningham said:

We run a 3" Magnaflow on a 3L engine and have never had a noise issue, including NCM and AMP which are particularly picky on noise.

 

Do you mean a 3" straight through like a glasspak or a one of their turbo mufflers with 3" inlet and outlet.   We have a 3" glasspak style (knock off) on our 2.4 liter 4 cyl and it is too loud for my liking,

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10 hours ago, tneker said:


 

 

Do you mean a 3" straight through like a glasspak or a one of their turbo mufflers with 3" inlet and outlet.   We have a 3" glasspak style (knock off) on our 2.4 liter 4 cyl and it is too loud for my liking,

 

It's one of the straight through 3" in/out mufflers.  Verified on the dyno on my car to rob less than 1hp. I can't say this is the exact one but looks just like this.

 

image.png.18fcf3f239e306d2e1d40fd9383d5ec5.png

Edited by Burningham
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I've done the following on a few miatas:

 

Cat delete, then a small resonator section at about the end of the transmission.  Once past the diff, make a right turn and hang a thrush/cherry bomb that exits just before the edge of the bumper.  The glass-pack's can be cut like a salami and take out how ever much you need, then weld them back together.  For the miata they end up about 16" long.

 

On my SCCA car we had this set up, dyno'd the car in then pulled the secondary muffler.  It was immensely different for noise while increasing the HP by 1 (yes one HP) across the whole curve.  These cars usually blow in the low 90's when there is a dB meter posting sound levels.

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I essentially use this system (http://mandrelbendingsolutions.com/spec-miata-race-exhaust/) on my spec miata and it met the Laguna Seca requirement of 90 dBa fine.  I do have a 90 degree elbow on the end of the exhaust pipe, so don't know if that makes a difference.  I use the same muffler on my 1st gen RX7 along with a racing beat presilencer and 14" Magnaflow 4" diameter muffler (which I am pretty sure is doing nothing now).  The car is even quieter than the miata and has raced at Laguna seca multiple times without any sound issues.    

 

Carl

 

PS  The miata uses the stock exhaust manifold per SM rules and the RX7 has a racing beat "short" header.

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