After reading a lot about different inserts and the battle of noise vs performance, I decided to make my own.
Here are the details.
Rules: It has to be easy to make and relatively inexpensive.

I have heard many good things about Magnaflows only $25 each so I started there







I ordered 2 exhaust cone adapters from https://www.coneeng.com/conical_products.html\
note, they only take orders by phone, good people, shipped same day $14 each





Cone will be welded to end of muffler. The cone is 2.5" to 4" and when placed inside the side pipes it sits perfectly
right where the 4" pipe widens a bit to slide on to the header.

NOTE!! I added a section of exhaust 2.5" tube (not in photo) between the cone and the muffler. I want the overall length to fit the side pipe and terminate right before it reaches the
side-pipe turnout exit. I was told to put the mufflers as far down the exhaust line as possible. Not sure it makes a difference but... I'm doing it
At the other end of the muffler I tack welded a 2.5" x 3.5" adapter -purchased a local parts store for about $6
The 3.5" final will leave 1/4" clearance around the end of the insert.







The final product
Left: insert - Cone to 2.5" pipe to muffler to 2.5" - 3.5" adapter
center: I wrapped the system with exhaust header tape - 2 things happening here:
1. I am hoping to reduce heat on the side pipes so I can avoid heat shields I do not like the way they look but
am also married to a wonderful lady who does not want leg burns....
2. I wrapped the header tape several times around the end (top in image) so it slides snugly into the side pipe.
Right: Side-pipe


The system is a snug fit (by design) It slides in until the cone sits down against the tape in the side pipe. I should not vibrate or rattle at all.


Cone slid down in pipe


Exit of side pipe the insert stops just short of the turnout


Total cost doe inserts
2 Mufflers - $50
2 Cones - $14
1 2.5 pipe $ 8 cut in half
2 2.5-3.5 adapters $ 5
1 header tape $14
Total $92 or 41 per side

This is a true budget build.
If it is too loud, then I'll be "one of those guy" for a while then order a quieter insert.
If the header tape works a bit, I may add more around the muffler. there is clearance for another layer or 2 of tape.

Now, as I write this it is exactly 0 degrees outside.....
When spring arrives and it warms up, I will fire this thing up and report back on the sound.

1968 427 with cam.... convertible She's gonna roar!

 

 

Great work Tom. Thank you for the idea and write-up.
Will be most interested in the resulting sound.

Steve

 

Thanks for posting this! I just picked up a set of headers, and was thinking about how to do exactly this, both for sound and for burnination prevention.

FWIW, the PO of my headers had welded some glasspacks to the collector, but assures me the 4" pipe still slides over them, even when installed. We shall see.

 

Nice work, and it keeps your outside pipes from burning flesh !

 

Very nicely done. Except for the brand of glasspacks, I built the same setup years ago for my Hooker sidepipes. When I fired it up in the garage, I knew it was too loud for me. A short trip around the block verified that and I pulled the inserts out that night. I ended up with the STS baffles. Your inserts may be quieter than the brand I used.

 

The only possible issue you may have in that glass-pack mufflers wear out quickly - 1-2 maybe 3 years.
It looks like you could cut them off if needed, The cut would be hidden so doing it perfect would not be an issue....
Good luck!

 

OK All.
The system is installed and... It is too loud... I was kind of afraid of that....
It sounds incredible but too loud.


It's funny but for 2 days driving around, I have never got so many thumbs up and cheers!
There is a group of people out there that really like loud vettes.

I have just order a set of spiral baffles... lets see what happens....

Oh the header tape worked great. The outside pipes were running about 140 after a nice cruise.

 

Yeah, a certain amount of civility has to be maintained, huh.
Good luck on the re-pack.

Steve

 

Sorry that it did not work out to your expectations but huge thumbs up on the build and the initiative to do it yourself. You are right, it DOES sound incredible but I can see how that would be annoying long-term.

 

Very cool how you fabed that up, sounds great to me🍻

 

Sweet thunder has some inserts that have a layer of packing, I'm not sure how much quieter they are. I do like the header tape on yhe insert I may try that instead of those ugly shields. Otherwise I will require long pants to ride with me.