Muffler specs

[C3L81]

Looking to change my mufflers to add a small amount of HP and some nice throaty sound to the car. What are the specs of our mufflers? Looking to get the size that will make my job the easiest. Im leaning towards Flowmaster 40 series, but taking recomendations. Thanks!

 

[C3L81]

2.5 right? Anyone have magnaflows?

 

[hdkeno]

I also am thinking about changing my stock mufflers. I do like the flowmaster series,have them on my Silverado.
But the dynamax mufflers are supposed to be good also. heard them on a friemds 1980 converted to true duals and they sounded okay,nothing spectacular. Let us know what you decide. ken

 

[C3L81]

Corvette central has pairs of magnaflows for $160, I have heard nothing about good things from them, leaning towards them or Flowmaster 40 series. I have ruled out Dynomax. I think I might change the C Converter too, I think she might be close to clogged.

 

[Peer81]

I'm also thinking about the Dynomax (stainless steel) and a stainless steel true dual. Now i have a 700r4 the original exhaust doesn't fit anyway.
I'm curious why you ruled out the Dynomax..

Groeten Peter.

 

[mdazzo]

Flowmaster 40 series

just finished installing Flowmaster 40 series on my 79 with true dual also installed a cross over for balance.it sounds great.I was concerned about possible cabin noise,so i pulled the seats and rugs and installed
a sound and heat shield.I am able to have a conversion and listen to the tunes with no problem.... and still enjoy the new exhaust ......hope this helps
volksbugusa...mastic,,,new york

 

[C3L81]

No reason really for ruling out the Dynomax other then the price and performance of magnaflows or flowmasters. (im pretty set on magnaflows now from corvette central) Im sure Dynomax are great, I just decided on the magnaflows. I might go true duel in the future as well, but cant afford it right now, so im going to go to a high flow cat and magnaflows mufflers. That will run me 300 for all of it from cc. Seems reasonable

 

[Evolution1980]

Looking to change my mufflers to add a small amount of HP and some nice throaty sound to the car.

You will likely change your sound a little bit, but not a whole lot. As for a "small amount of HP", that's probably all you'll get by switching to a different muffler. It likely won't be enough to notice on the butt-dyno, however, an increase in sound can help the feeling of some improvement even if there really isn't. As long as you're happy with your purchase!
The noticable increases in our cars don't really show up until you dump the restrictive exhaust, starting with the OEM manifolds and then getting rid of all the smog stuff. Other noticable increases come from things such as...dropping in a beefy crate engine :L

 

[C3L81]

Switching to a high flow cat and performance mufflers will certainly add some hp, even if it is a small amount thats fine with me because if I need to switch it back its very easy. As for smog equipment and motor, im not about to ruin the value of my low mileage car to so something I dont really need to do.

On that note, would headers and True duel mess with my ecm if I still have a 02 sensor?

 

[Evolution1980]

As for smog equipment and motor, im not about to ruin the value of my low mileage car to so something I dont really need to do.

I didn't say throw it out... :L I still have all mine in a box, however, when I get around to it, it's headed for eBay.

On that note, would headers and True duel mess with my ecm if I still have a 02 sensor?

That's outside my knowledge of the vehicle. If ya really want to know, I'd post that as a separate thread in the general C3 tech forum...(more exposure)

 

[smithjw]

If you still have the original exhaust system with original cat, and you suspect that it might be clogged, you will definitely get a HP increase by switching to a new high flow cat. I had this same problem. The original cat had deteriorated so badly inside that one of the air passages collapsed and was choking the engine. I put on a new high flow cat (from Random Tech) and also replaced the original mufflers with the twin tip straight through type muffler you can get at Ecklers or Mid America. I like the sound of the straight through design as compared to the big can style mufflers that you are looking at.

 

[Koop]

I have Magnaflows on my Vette, they sound good and they get loud when I stand on it and best of all they put the sound out the back of the car. I've been using Magnaflow only for about 3 years now. They sound awesome on my LS6.

I've had Flowmasters, they create to much interior resonance for a plastic car IMO.

 

[Evolution1980]

I've had Flowmasters, they create to much interior resonance for a plastic car IMO.

I always equate the Blowmasters to that well-known Mustang sound...

 

[C3L81]

Thanks guys for the feedback. I think I know what im going to do...pretty much set on a new High flow converter and Magnaflow mufflers. Im still lost on what size the inlets on the stock C3's are.....2.5 I assume?

 

[Evolution1980]

Im still lost on what size the inlets on the stock C3's are.....2.5 I assume?

I think they are actually 2.25". That's what I have now. I don't know why I (my mechanic) would've downsized from 2.5" when I (he) redid my exahust.
I still have my stock exhaust at home. I can do a measurement of it later tonight when I get home.

 

[Koop]

I always equate the Blowmasters to that well-known Mustang sound...

BLOWMASTERS! LOL With a nice Bloomin' flower turbo and a blowmaster fart can a ricer will sound pretty mean!

I don't know what size exhaust you have, but with the expense of the new cat and mufflers you may as well get bigger pipes!

I had 2.5 put in mine.

 

[Evolution1980]

I don't know what size exhaust you have, but with the expense of the new cat and mufflers you may as well get bigger pipes!

He may lose some bottom-end torque going to a larger diameter. Given the base car's performance, an increase or decrease in torque is going to be more noticeable than a change in HP, so keeping what torque he has (and not diminishing it) should be first on his list when considering upgrades, IMHO.
Also, he's looking to keep costs down. If he was going to replace all his piping, he might as well go true dual exhaust but... "... cant afford it right now, so im going to go to a high flow cat and magnaflows mufflers."

 

[Peer81]

And your stock short headers are only 2 or 2.5" so without changing them there will be no effect anyway.

Groeten Peter.

 

[Evolution1980]

Interesting (to me) what I found about my stock exhaust...

Where the front y-pipe mates up to the exhaust manifold, it's not even 2" in diameter! It's just about 1.75" on the inner-diameter,

The outside is flanged for mating up to the exhaust manifold. It looks to be about 2-3/8".

The stock rear Y-pipe is 2.25" as I expected, although it certainly looks bigger in some areas along the way.

...this leads me positing this question... If the initial inner diameter coming off the exhaust manifold is so small, does it really need to be any bigger along the way??? Wouldn't exhaust flow be restricted by the smallest part of the system once it reaches the collection point (the end of the exhaust manifold)???
:confused

 

[Peer81]

I'm afraid you're right
I'll look at mine next week. I know that 81's still have 2" short headers and 82's have 2.5". But i never measured the inner diameter.

Groeten Peter.