a scientific study of sound in the ST cabin...

From a prior post more changes... stifling the sound we got the CFM Performance 4-0300 Symposer Delete with Pressure Port for 2013-2016 Ford Focus ST to install on our 2016 FoST.

our FoST with the Cobb 3" Catback is quite boomy... so I measured with an app on my iPhone6  - yikes!  yes that's 98.1 decibels

Noise Source	Decibel Level	Decibel Effect
Boeing 737 or DC-9 aircraft at one nautical mile (6080 ft) before landing (97 dB); power mower (96 dB); motorcycle at 25 ft (90 dB). Newspaper press (97 dB).	90	4 times as loud as 70 dB. Likely damage in 8 hour exposure.

So - in the sense of not losing our hearing.. I installed the sound symposer delete today by CFM Performance - an inexpensive $29 modification!

Here's how it gets installed :)

First you remove the engine cover, simple enough just tug at the 4 corners and it 'pops' off...

next, you remove the sound symposer and hose from the front of the engine - 8mm wrench works like a champ!

notice the oil residue - ick!  seriously!?

Now you mount the blocking plate using 2 of the 3 bolts you removed - looks slick!  removes a lot of the bulk by the front of the engine!

Here's the rest of the setup, engine cover back on sans symposer

here's where the symposer valve used to be... a simple Torx-20 bit to remove it - then ziptie the wiring out of the way...

and add the blocking plug to the firewall inlet (the little 90 degree elbow on top)

now the amazing part... went out for a drive... can't get it over 89.6 dB - that's a HUGE drop!

just for reference again:

100 dB

8 times as loud as 70 dB. Serious damage possible in 8 hr exposure.

90 dB

4 times as loud as 70 dB. Likely damage in 8 hour exposure.

so by using a $29 mod - we've reduced the loudness by 4X - it's still quite loud, but not painful anymore!