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Junior Charter Member
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847 Posts
I’m working on quieter pipes right now,
I’ll post a follow up but to start off my basically stock 302 (bored slightly to 306) measures 117 decibels at 4000rpm. My home track has a 100db limit so I’ve got some work to do. Note, that this reading was probably inaccurate as the sound meter was on the ground near my truck so there was a lot of echoes happening.
 

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I have not used a sound level meter on the installation of the little glass pack mufflers before or after. but I can tell you that the sound is about 50% quiter than before with the wide open side pipe. My fix for the Cobra was for financial reasons and I did not want to start all over on the header exhaust system, as anyone will tell you, installing the FFR side pipe on the Coyote engine is very difficult, due to access to the header bolts!!!
Looks like you riveted some metal shims to wedge/bolt on the glass pack muffler. Is it just the one shim? I take it this increases the overall length of the side pipe by about 8”, yes? I’d appreciate if you could post some part numbers and source, I have to try something.
 

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122 Posts
I think a pair of turbos could really keep the noise down :)
 

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FFCobra Captain
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11,720 Posts
I bought a pair of inserts from Whitby a back around 2015 or 2016. They really cut the harshness out of the exhaust note. When I upgraded my motor to a 347, I couldn't drive even at low speed without my ears hurting (actual pain...not just 'the car is too loud). The inserts helped a ton. I still use ear plugs on long drives, but that's mostly because the wind-noise leaves with a dulled hearing after a while.

I have details in here:

I have them in the car now just ask shown, but you can tone them down even more by wrapping them with some steel wool.
 

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Premium Member
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302 Posts
Are the GasN pipes not quiet enough? They seem much quieter than the FFR pipes, especially after those pipes blow out all of their glass pack
 
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