Muffler upgrade

[chris989]

Hello All,

I wanted to share my experience. I would have never believed the difference if someone just told me.

My build is simple. 350 tbi with a small lunati cam
.437"/.454"
207/213 @ .050
250/256
header, 2.5-3" exhaust, stock chip.
https://67-72chevytrucks.com/vboard/...d.php?t=696544

I have been running a 3" high flow cat and a 3 inch turbo muffler (necks down to 2.25 inside) and at 3500 rpms it didn't have a lot of pull left.



I always thought it was the cam or heads causing this. My state lifted the smog requirements so i finally tried a new set up. My motor pulls easily to 4500 rpm now before the TQ falls off. It is night and day different. If I had not driven it both ways i would not have believed it.

The new set up is a glass pack along with a Jones Max Flow.
https://www.summitracing.com/parts/JEX-MF2289



Anyway,, before this I was thinking about a set of heads or a 406 dart block for more stroke. I am glad I didn't. I am excited to see if my mileage increases on my next camp trip while towing.

Chris

[blazer2007]

What is it suppose to do with 2 mufflers attached like that and is it loud or nice and quiet ?

[chris989]

Originally Posted by blazer2007

What is it suppose to do with 2 mufflers attached like that and is it loud or nice and quiet ?

I had the glass pack laying around but by itself it is too loud.

I run a Jones max flow on my 78 ford f250 and it sounds awesome but alone it would be too loud for my daily driver.

the two together have a great sound while being mostly quiet. Get in the gas and it sounds great and at cruise i can hardly hear it.

[cadillac_al]

The catalytic must have been clogging.

[chris989]

Originally Posted by cadillac_al

The catalytic must have been clogging.

That happened to a friends camaro way back in the 80s. That car would barely run and we messed with it for a week until we cut the cat off. Someone probably ran leaded gas in it.

I find it odd that all the turbo mufflers neck down to ~2" inside no matter the ID of the tail pipe.

[mongocanfly]

hmmm.... my mufflers are 2-1/2" pipe and id all the way thru..
they are knockoff magnaflows...1 set is magflow, the other is maxxflow after they changed their name
not sure what a turbo muffler is...is that a brand , or just the style?

[chris989]

Originally Posted by mongocanfly

hmmm.... my mufflers are 2-1/2" pipe and id all the way thru..
they are knockoff magnaflows...1 set is magflow, the other is maxxflow after they changed their name
not sure what a turbo muffler is...is that a brand , or just the style?

It is style and look like this inside

[chris989]

I wanted to double check the cat before i posted again. My cat is 100% hollow inside. Just for show.
All of the resistance was in the muffler. out of curiosity i might cut it open to see what happened. It came from Midas locally because I needed it and they where the only ones with it in stock at the time. (covid).

[mongocanfly]

I had a cat disentergrate one time and plugged up my muffler on a s10 blazer I once had, it couldn't get out of it's own way til I changed the muffler

The maxxflows/magflows I have are a straight thru design , the tube inside the muffler is full of holes that I assume is surrounded by some sort of sound deadener, they arnt to bad loud, nice mellow tone
I drew the tube path on mine on this pic

[Mike C]

Originally Posted by chris989

I find it odd that all the turbo mufflers neck down to ~2" inside no matter the ID of the tail pipe.

The Walker SuperFlow aka DynoMax mufflers are true size all the way through. They are the old Sonic Turbo of the 80’s designed by David Vizard.

[mongocanfly]

I've got a set of Walker super quite high flow 2-1/2"...they step down to under 2in as soon as they go into the housing..