1969 GT350 Muffler replacement question

[Cobra350]

OK, being a purist I prefer my 69 Hertz GT350 to remain as close to bone stock as it has always been.  And now comes the 'but'.

Hopefully we can agree one can't take the teenager out of the man, so when my initial restoration presumably stock style muffler wore a couple of holes in after years of occaional cruises I actually have been enjoying the sound.  It seems the off the shelf replacement really tames the 351W.

So, any suggestions on a throatier replacement?  So far all I've come up with is a stock number for Flowmaster 42582.  Hoping it will fit with the correct pipes in place.  I was abhorred at the first attempt when the muffler shop suggested we alter them so they could use something they had in stock. Omg.

So, need a good and good sounding muffler, do I stick with the Flowmaster?

Thanks!

[Scott Fuller]

Just make sure the inlet and outlet pipe distance is the same as stock or you'll be modifying the tailpipes too.  And some aftermarket mufflers are too "thick" and don't have the proper room between the tank and rear end.

Scott

[Cobra350]

Thanks Scott!  And the irony of finding your products just after my posting, terrific to see what you are offering we enthusiasts!  Very nice work to say the least.

[crossboss]

Go with the Flowmaster. The stock trans-vers muffler is very restrictive.

[427hunter]

Walker turbo mufflers don't drone like flowmasters and sound great.

[cj750]

Walker turbo mufflers don't drone like flowmasters and sound great.

I'm a fan of Walker turbo mufflers, but haven't been able to find one for a transverse mounting application. Do you have a link or part number?

[Bob Gaines]

 You didn't say if you currently have a original exhaust system like what was installed at the factory / exact duplicate to the factory like what Scott sells or a aftermarket replacement exhaust system that is in the same configuration as Ford ( two generic after market resonators and a generic aftermarket transverse. With that said the transverse muffler dramatically heats up the fuel in the gas tank which is not a good thing and can be a source of carb problem symptoms. If a aftermarket exhaust then I would not feel bad by taking out the transverse completely if it were my car . The aftermarket exhaust is already substantially different looking then "bone stock". Kind of like being a little pregnant . Ether you are or you aren't. With originality sensibilities in mind It doesn't make positive use of your time to quibble about replacing a portion of that aftermarket system with another after market part. If wanting to personalize the sound to your taste do what needs to be done without a transverse with a clear conscience is my perspective.

[shelbydoug]

There is no simple answer to the exhaust question other then do you want it as close to stock as possible or something else?

Generally speaking the 1970 dual exhaust system is a much better system for a lot of reasons and if you are going in that direction, building your own, you don't need the resonators if you use the Walker or the Flowmaster "Turbo" mufflers.

So how to build the system is an entire "chapter" all of it's own including what diameter pipes you should use, etc.

Fuller's is as close to stock original as you are likely to find including the disappointment in the designed in restriction on flow and power.

Personally I think 2-1/2" Turbo Flowmasters sound the best. I do not know of the transverse version and I know of no one using them. So I think that you are pretty much on your own there BUT part of the issue here is going to be the diameter of the pipes and 2-1/4" may have been the stock high performance size but they are restrictive and have a different sound and to me sound like a stuffed up vacuum cleaner.

[427hunter]

Walker turbo mufflers don't drone like flowmasters and sound great.

I'm a fan of Walker turbo mufflers, but haven't been able to find one for a transverse mounting application. Do you have a link or part number?

I cant find the walker one but you can try the Thrush Turbo Mufflers 17654 - make sure you confirm the dimensions are the same. Summit has them.

[prototypefan]

You didn't say if you currently have a original exhaust system like what was installed at the factory / exact duplicate to the factory like what Scott sells or a aftermarket replacement exhaust system that is in the same configuration as Ford ( two generic after market resonators and a generic aftermarket transverse. With that said the transverse muffler dramatically heats up the fuel in the gas tank which is not a good thing and can be a source of carb problem symptoms. If a aftermarket exhaust then I would not feel bad by taking out the transverse completely if it were my car . The aftermarket exhaust is already substantially different looking then "bone stock". Kind of like being a little pregnant . Ether you are or you aren't. With originality sensibilities in mind It doesn't make positive use of your time to quibble about replacing a portion of that aftermarket system with another after market part. If wanting to personalize the sound to your taste do what needs to be done without a transverse with a clear conscience is my perspective.

If you are driving the car Bob makes a very valid point about the transverse muffler heating up the fuel in the tank. Has anyone installed just the resonators or mufflers in place of the resonators and then had tailpipes routed to the aluminum collector? I'd be quite curious how a system set up like this would sound/perform compared to original.

Anyone done this and care to comment?

[Bob Gaines]

You didn't say if you currently have a original exhaust system like what was installed at the factory / exact duplicate to the factory like what Scott sells or a aftermarket replacement exhaust system that is in the same configuration as Ford ( two generic after market resonators and a generic aftermarket transverse. With that said the transverse muffler dramatically heats up the fuel in the gas tank which is not a good thing and can be a source of carb problem symptoms. If a aftermarket exhaust then I would not feel bad by taking out the transverse completely if it were my car . The aftermarket exhaust is already substantially different looking then "bone stock". Kind of like being a little pregnant . Ether you are or you aren't. With originality sensibilities in mind It doesn't make positive use of your time to quibble about replacing a portion of that aftermarket system with another after market part. If wanting to personalize the sound to your taste do what needs to be done without a transverse with a clear conscience is my perspective.

If you are driving the car Bob makes a very valid point about the transverse muffler heating up the fuel in the tank. Has anyone installed just the resonators or mufflers in place of the resonators and then had tailpipes routed to the aluminum collector? I'd be quite curious how a system set up like this would sound/perform compared to original.

Anyone done this and care to comment?

Done the change many times over the decades.  The exhaust without the transverse was the go to configuration for driver cars needing exhaust replacement the first time from new in the 70's . It is however hard to describe for me the sound in words. The sound is louder without the transverse but not extremely . Of course that is a matter of perspective and a matter of what you use as resonators . The burble is different.  Don't ask me to describe what the burble is. Hopefully someone else can help better to describe.

[shelbydoug]

You didn't say if you currently have a original exhaust system like what was installed at the factory / exact duplicate to the factory like what Scott sells or a aftermarket replacement exhaust system that is in the same configuration as Ford ( two generic after market resonators and a generic aftermarket transverse. With that said the transverse muffler dramatically heats up the fuel in the gas tank which is not a good thing and can be a source of carb problem symptoms. If a aftermarket exhaust then I would not feel bad by taking out the transverse completely if it were my car . The aftermarket exhaust is already substantially different looking then "bone stock". Kind of like being a little pregnant . Ether you are or you aren't. With originality sensibilities in mind It doesn't make positive use of your time to quibble about replacing a portion of that aftermarket system with another after market part. If wanting to personalize the sound to your taste do what needs to be done without a transverse with a clear conscience is my perspective.

If you are driving the car Bob makes a very valid point about the transverse muffler heating up the fuel in the tank. Has anyone installed just the resonators or mufflers in place of the resonators and then had tailpipes routed to the aluminum collector? I'd be quite curious how a system set up like this would sound/perform compared to original.

Anyone done this and care to comment?

Done the change many times over the decades.  The exhaust without the transverse was the go to configuration for driver cars needing exhaust replacement the first time from new in the 70's . It is however hard to describe for me the sound in words. The sound is louder without the transverse but not extremely . Of course that is a matter of perspective and a matter of what you use as resonators . The burble is different.  Don't ask me to describe what the burble is. Hopefully someone else can help better to describe.

Listen to ANY Mustang with an aftermarket Borla Exhaust. That is what they will all sound like. The difference is more clearly heard from a distance. Not close up.

There isn't enough change in the length of the pipes on any Mustang to have changed the frequency over the last 50 years.

The most different sound to the exhausts on stock systems is with the 69 Shelby because of the center exit and the rear exhaust exchanger.

That is heard largely at idle.


I do not think that there was much thought at all put into the production systems, other then they needed something to bolt up to something here to go over there and have some shiny baubles on the tips for the kids to envy.

Similar to the tire selections. "This is it. Pick A, B, or C".

[crossboss]

Walker turbo mufflers don't drone like flowmasters and sound great.

I'm a fan of Walker turbo mufflers, but haven't been able to find one for a transverse mounting application. Do you have a link or part number?

I cant find the walker one but you can try the Thrush Turbo Mufflers 17654 - make sure you confirm the dimensions are the same. Summit has them.

Alex,
I believe you are referring to the Walker 'Dyno-Max' line of mufflers. They are an excellent choice.

[427hunter]

Walker turbo mufflers don't drone like flowmasters and sound great.

I'm a fan of Walker turbo mufflers, but haven't been able to find one for a transverse mounting application. Do you have a link or part number?

I cant find the walker one but you can try the Thrush Turbo Mufflers 17654 - make sure you confirm the dimensions are the same. Summit has them.

Alex,
I believe you are referring to the Walker 'Dyno-Max' line of mufflers. They are an excellent choice.

Scott, it looks like the the 17654 is a Dyno-Max - does walker own thrush now?

[Dennis Y]

Long time fan of Magnaflow here. Had 1 on my last 2 trucks and love the sound. Plan on running them on the Shelby when it's ready to go. Just getting the shell back together right now. Years ago ran Thrush Hush ovals on my small block Maverick but those are long gone.