because y8sfabbed.

https://www.miataturbo.net/attachmen...ine=1334774092

https://www.miataturbo.net/attachmen...ine=1334774059

The cutouts would be for dyno days/track events, the other 99% of the time it would be nice and quiet.

My miata had the same magnaflow as most of you guys and it was so much quieter then these duals.

quite and exactly the same speed, spool, torque, hp, etc.

I have a smaller, round magnaflow model.... 3". I keep ear plugs in the glove box for long drives.

https://www.miataturbo.net/attachmen...ine=1334784929

http://i165.photobucket.com/albums/u...a/107_0903.jpg

Mines..

https://www.miataturbo.net/attachmen...ine=1334836789


Wind noise on the interstate with the top down is louder.

Tested mine with some free dB meter app, soft top and windows are UP for the tests.

idling in traffic: 55dB
engine off, at stoplight: 49-50dB

cruise top up (40-60mph): 72-74dB
cruise in nuetral same speeds: 67-68dB

WOT: 77-80dB

stereo on: 85-90dB


at worst, the exhaust is adding 7dB to the road/wind noise in cruise. At WOT, most the noise is coming form my intake.

Picked up a free app (Noise Meter) and tested this morning. Soft top and windows up, no stereo.

Exhaust is 2.5", no cat, straight through to a 14x9 Magnaflow.

Idle 53dB

5th gear cruise:
40mph 60dB
65mph 74dB

Mine is retarded loud. Ive got one of the quietest exhausts and it doesnt help.

Ive got road noise from the 275s (upgrading to a better tire to reduce noise). Sound from all the gaps. Realigning all the fenders and doors made a difference, and realigning the windows to seal better, helped. Gonna do ttop seals to kill the last of it. And when I finally get around to putting the carpet in, Ive got sound deadener, closed cell foam and some jute im putting down.

I cant stand a loud car anymore.

yeah my road noise is louder than anything else.

same here. i have a big magna muffler with 3inch from the turbo. cruising 60-80 on the highway the car is really quiet.

I have to wear earplugs because if I don't, and go WOT and QSV and WG open, I die.

In my old 3" setup, I still always wore earplugs.

When you guys measure dB you MUST measure dBA.

The 'A' weighting mimics the ear's response. Without it you get plain sound energy, and the bass will waaaaaay overstate the numbers.

The quietest straight-through muffler in cruise is probably the Dynomax VT muffler due to its spring loaded flapper:

https://www.miataturbo.net/attachmen...ine=1335057963

https://www.miataturbo.net/attachmen...ine=1335057963

I did one better and cut the flapper out and installed it after the bigassest Magnaflow 3" muffler that fit. The effect on drone at light throttle was dramatic:

https://www.miataturbo.net/diy-turbo-discussion-14/my-3-custom-exhaust-spring-loaded-flapper-valve-62488/

I really like the dynomax, but when I looked they didnt have one that I thought would work well for the fbody.

2OTL for Opti. I also liked having the stock WS6 catback with dual cutouts before the Y. I currently have a HUGE Magnaflow on the Miata now.

I'm going to pick up a DBa meter next day I have off.

I'm running a 3" catback my self.. giant magnaflow muffler like 24" or something along with a 3" resonator and a 3" cat... Quiet as stock or a tiny bit louder. I barely hear it over the turbo whistling.

If i was to do it again, i'd run a cutout right before the cat right after the sensor and leave the stock exhaust on.

Currently its painted black.

https://www.miataturbo.net/attachmen...ine=1335068138

Any words on the reliability of that flapper? I had heard rumors that it didn't last as long as one would like (forever, really). I like the idea, but I want my exhaust to be forever, like a diamond.

I used a free app for my phone. I realize it's not even close to accurate, but I gave a few reference points to get the idea.

one more point of reference, my office measures 44 "dB"

The DSM/EVO guys have been running them for a while, and they tend to get less than a year out of them before they start to clatter at idle. I guess the little fiberglass cushion on the end of the flapper wanders off over time. They are moving a LOT of air, and run their cars quite a bit harder than most of us do, though (EGTs, race gas, etc) so one might last forever in a 300whp Miata where it only lasts months in a 600whp EVO. They also run them in the muffler, where JasonC runs his after the last muffler, so it will run MUCH cooler like that.

I now haz flapper backpressure data, suckaz!!

Difference between flapper normal, and flapper wired open, is < 0.2 psi!

I assume that's at WOT? What is the total pressure?