Street car mufflers
 

I need a recommendation for new mufflers. I'm putting my '69 Firebird convertible back to street duty. It has a Spott's 455, ported on 6X heads, 9:1 compression, Comp Cams HE274 cam, '69 iron intake, 7029268 q-jet, long branch manifolds into a PYPES 2 1/2" exhaust with an X crossover, th400 with 2800 stall converter and a 3.42 gear.

I am still using the Dynomax Race Magnums. The exhaust is WAY too loud. I cannot hold a conversation, and the drone is a PITA. I'd like something much more tame sounding, but will not stifle the performance.

Any thoughts are appreciated!

Thanks

I run Hushpowers on my 69 bird and on my 421 63 lemans.I had to use a H pipe to kill a 2K RPM drone.They did not like a X pipe.2 1/2 all the wayback over the axles.Tom

I'm a fan of PYPES Race Pros myself, but the Street Pros are louder

http://pypesexhaust.com/p-21709-1964-1972-gto.html

I find my Pypes Race Pros obnoxiously loud, I literally hate them. Not bad at idle, but way to raspy/glass-pack-sounding with any throttle. They are on a car that I won't have back on the road for a bit, or else I would have changed them already.

On my T/A clone, I've been pestering Tom Hand, and doing a lot of other research. I've pretty much decided on Borla ProXS for max performance with minimal noise.

I run the Race Pros on my convertible- they aren't what I'd call quiet, but they're far from obnoxious. My wife thinks they sound good, for what ever that's worth. :D

If you want quiet without totally killing the performance, get Dynomax Super Turbos.

another vote for race pros or the dynomax ultra flow, they are a straight through design with fiberglass matting in the case. very mellow at idle & cruising but they do get louder at WOT... far from obnoxious & definitely not glass pack sounding on my car with full length 3" pypes exhaust & an X pipe. do a search, theres lots of threads with exhaust sounds.

the dynomax superturbo will quite things down a lot, almost too quite for cars like this.

I have a 67 Firebird 400, .030 over, cam, LB manifolds and Pypes 2.5" with Racepros. Great sound but not excessively loud.

Being a convertible I completely understand the need for a quiet system. I couldn't stand our convertible with the top down until I fixed that issue.

On the convertible I'd either go with the Dynomax Ultraflow (20" case if you can fit it), or the Dynomax super turbo which is a tad quieter. This is assuming you're running a dual muffler setup.

I also run both Pypes race and street pros and I find the street pros quieter. Completely different from what Pypes claims. What's even more interesting is that the Race pros are on a 2 1/2" true dual setup with H-pipe with a smaller engine and the Street pros are on a 3" dual setup with no cross over at all on a BBC that has 100 more cubes, yet the street pros are quieter.

If you want the transverse system that tucks up nicely on the F-body, I run 2 of the Pypes SGF-70 setups, which uses a Race Pro crossflow muffler. Here's a clip of that system on my bird, with factory RA manifolds and Pypes 2 1/2" down pipes. Quite honestly though, I think it would actually be a bit too loud for me if it were a convertible. But on this car it's actually very quiet inside with no drone.
My first pic for a Transverse exhaust system, especially on a convertible, is the Thrush 89021 which is actually made by Dynomax and uses their Super Turbo muffler design and an H-pipe. It's fairly quiet, much quieter than this Pypes transverse system. However the 89021 has been on backorder for quite some time now.

https://youtu.be/uIFkggwDY-8

I just installed the 3" 20" long Ultraflows in place of the 14" 2.5" versions and they are noticeably quieter. I would imagine the 2.5" 20" long mufflers would be pretty mellow but not much quieter than the 3"ers. The perforated internal pipe in the 2.5" mufflers is actually 3". At least they were as of a few years ago.

I have the Pypes 2.5" X-pipe and full tail pipes. I like my Magnaflows. Not loud at all in the car and very little if any drone. My wife says she can tell when I pull into the neighborhood though.

I went from spin techs to Dynomax ST to Dynomax VT. I had drone with the first two.

I love the VTs. Its all pretty quiet until you smash the peddle to the floor. I believe Dynomax is not selling them anymore but I think you can still get them. Lot of people had issues with them clanging. I never did.

How about Cherry Bombs? I've been running a set of them on my 66 and find they're quiet but sound good. Louder when you mash the gas and when you let off the gas they'll crackle and pop. Just like the old days back when they were a popular alternative to plain ol street mufflers. I've had guys asking what I was using and gotten good comments from them when they found out. A few have even switched to them after running the more "expensive" modern mufflers that are louder.

Dynomax VT
 

Dynomax VT on my street 455. NO DRONE and they sound great!

'Quiet' is a relative term, and you will get a million opinions. But, just to say, without sacrificing performance, the Dynomax Super Turbos are about as quiet as you can get.

Use all the normal steps too, like X or H pipe, largest case you can fit, etc., and you should be good.

.

I have a similar combo to yours. This is a 462, 9.5:1, Street ported 96s and the voodoo 704. Exhaust is Pypes x, street pros through tails. No drone at all when crusing.

https://youtu.be/Zj5w1fX17R0

The Dynomax Super Turbos are the quietest I’ve ever used on this type of system.

Race Pros are nice when you are at the lights beside Johnny Law or just cruising in and out of the neighborhood.
But step on it...and you are turning heads for a block around you.

I like the street pros too. The only muffler from Pypes I prefer. I've tried the race pros, they were just way too loud for me.

Your car sounds great by the way ;)

Your car sounds great by the way ;)[/QUOTE]

Thanks FJ, and for all the replies to my threads!

I went from Super Turbos to Goerlich Xlerators to Flowmaster 3 chamber to Pypes Street Pro.

Out of that batch, I think the Goerlich's were my favorite but I like the Street Pros I have now. They're loud when the car is cold but quiet down once things warm up. They have a nice idle sound too.

https://www.youtube.com/watch?v=7KoHcSF4SQw

A nice muffler and cheaper is the "Thrush Welded", they are a chambered muffler and sound really good. I will give a "nod to the Dyno Max Super Turbo as one of my favorite non racecar type muffler.