So I just did a compare of a Omega HHSL1 sound measuring device vs. my phone running the free android boy decibel meter app.

California law calls for measuring 20" away from the exhaust tip between 3k-5k. I just performed a 3k rev check.

--------------******** Outside ********
--------------------Omega HHSL1-----Phone
--------------------db-C / db-A---------db-A
1200rpm---------108 / 86 ----------- 93
3000rpm---------110 / 93 ---------- 96

#### not sure why my phones outside 3k value is different than the other day??

----******** Inside w-windows closed********
--------------------Omega HHSL1-----Phone
--------------------db-C / db-A---------db-A
1200rpm-------86-94 / 62 ----------- 60
3000rpm---------- 86 / 71 ---------- 72

inside cabin #'s are pretty close to each other when measuring in db-A

 

I think a reading from the driver side seat reving from 3-5k would be beneficial as well. This would mimic highway cruising, which is the main annoyance of exhaust drone.

 

I'll be posting stock results later.

 

From my thread: here we go again quiet cat back clarification needed

2005 Evo VIII
HKS 272/272, AMS GT35R
GTSpec Headers, Perrin 3" downpipe, CBE, HFC.

--------------******** Outside ********
--------------------Phone
--------------------db-A
1200rpm---------93 (distance 20')
3000rpm---------no data (no second person)


----******** Inside w-windows closed********
--------------------Phone
--------------------db-A
1200rpm---------73
3000rpm---------82

EDIT: HOLY ****! I just saw that your distance was 20" as in INCHES. I didn't read this post before I went out and measured... mine was 93 db at 20 FEET.

So from seeing these... It's pretty evident that my car is as loud as I think it is. I started it this morning and came back in to let it warm up, and when it idled down, the dishes were rattling in the cabinets.

 

Inside
Idle 950= 55
cruising 3k=75

Outside
Idle=83
3k=100

 

What exhaust wizzo? Is that stock?

 

I'll have to check this app out.

Way way back when at a drag race they had an audio contest going on and had a contest to see who had the loudest car. I placed 2nd at 137 dB in my 1994 Mazda MX6 V6. My buddy won at 141 dB in his Integra GSR. I think they measured from the same distance. I don't even want to know how loud my EVO is.

 

Started as an eBay tbe. I added a 7" round muffler to fit in the test pipe spot. I also added a 1ft 4" round resonator between that muffler and the rear one. Pretty quiet I think

 

I'm running a 2.3 AMS stroker kit, 4R cams, headwork, Peakboost GT35R, and tons of other supporting mods:

Exhaust setup: downpipe, testpipe w/ boost actuated cut out and stock catback.

Here is the cutout I'm using: http://www.spracingonline.com/store/...ctivated_/3673

Using the phone app my db readings were at 20 inches were:

78 db at idle
80 db at 3500 rpm

70 db in cab cruising at 3000 rpms.

 

^ Awesome.

Does it feel like you lost any low end peformance when running through the oem muffler?

is the oem muffler modded in any way?

 

It's got a boost actuated cutout. I did a double take also, was hoping it was running through the muffler.

I'd like to see the db reading under load at 3k rpm

 

Buschur Turboback with small magnaflow and SD rear.

Inside with the windows up:
idle @ 1100= 78db

Outside 20" from muffler
idle @ 1100= 96db

The car wasn't at its loudest tonight and I didn't have a second hand to do a 3500rpm test.

 

Honestly no, I can't say I noticed any low end performance loss.

No, the oem muffler is not modded. The way I look at is I spend 95% of the time cruising, so why have an exhaust system made for just 5% of my time at WOT.

The cutout starts to open at around 5 psi and is fully open at 11 psi. I really like this setup above anything else I have tried or seen.


I updated the post above with cruise db at 3000 rpms.

Next time I'm out doing WOT pulls I'll take some readings. It definately growls when the cutout is open.

 

Might want to list what app you are using too as some read better then others

 

man... i am confused.

i am definately considering a 3" exh w/qtp near the oem muffler.......qtp triggered off of tps or boost