Anybody installed 18" mufflers?

[Kaspar 21]

I'm considering installing 18" Magneflow mufflers on my '69, but am worried there isn't enough room for them compared to 14".

Has anybody done this or know if there is enough room?

Thanks in advance /K

[Red Sportsroof 10]

I had a set of magnaflows on my Sportsroof a few years ago, they seemed to work okay. I used downturns out of the muffler instead of an exhaust pipe to the back. I changed it back to original and the aftermarket transverse muffler was a joke. It ran like it had potatoes stuck in the pipes and it was a dog. The greatest sound though is with the original resonators and piped out the back. Driving the freeway it sounds like a million and its not too loud but people know you've got something going on.

[69cat&stang 10]

don't think you will have room for that long of a muffler.

 

just my 2 cents but Flowmaster 40's sound a lot better on the muscle cars, to me the magnaflows are just way too quiet.

[MikeStang 247]

Depends on how you are willing to position them under the car really

[Brian Conway 264]

I am running The FlowMaster 40 series on my car. Exactly the same set up as on my 65 GT dual exhaust car including the hangers. Muffler pack 13", 4" thick, 19" end to end w/2.25 inlet/outlet fittings. Brian

[sportsroof69 13]

I wouldn't put Flowmasters on anything, ever. Not only are they one of the most power robbing mufflers, but they're obnoxiously loud with a terrible TERRIBLE drone, that's almost unbearable. Nobody even turns around when they hear Flowmasters because they think it's just another redneck in a Chevy pickup.

[Brian Conway 264]

Well sportroof while I do admire your posted ET I don't share your opinion. Brian

[MikeStang 247]

I have run Slowmasters before.

They are louder than I like and have always had a drone.

They actually flow WORSE than most of the cheaper mufflers...Top 20 mufflers include if you can believe this Dynomax super turbos lol. Along with borla, spin tech etc.

This is proven by independent testing.

I have a CD somewhere with documentation of flow numbers and sound clips of about 50 mufflers.

The guys who did the testing flowed a piece of straight 3" pipe with no muffler to establish a base line then started bolting mufflers on...

I dumped my slowmasters for super turbos which were 1/2 the price and sounded nice and mellow till you pushed the go pedal to the floor them they came alive

[mwye0627 44]

I guess I have to take some exception to the title "Slowmasters" that some of you think of Flowmaster Mufflers.

I was the Crew Chief on an S-10 truck that was the 3rd member of the Flowmaster 7 second club.

In 1991, Flowmaster contacted us because at the time we had the world's quickest pickup truck. They wanted us to try some of their products to verify their ability to produce power while still being quiet enough to pass noise restrictions at certain dragstrips.

We settled on a set of 4.5" in - 4.5" out series 50 mufflers with a 4.5" turn out after the mufflers.

On our first pass with the mufflers we ran a 7.91 second ET @ 175 MPH at Norwalk Raceway Park. That ET corrected to sea level would have been 7.75 seconds. It has been documented.

Look up the Flowmaster 7 Second Club.

They also have a Flowmaster 6 Second Club.

[sportsroof69 13]

I guess I have to take some exception to the title "Slowmasters" that some of you think of Flowmaster Mufflers.

I was the Crew Chief on an S-10 truck that was the 3rd member of the Flowmaster 7 second club.

In 1991, Flowmaster contacted us because at the time we had the world's quickest pickup truck. They wanted us to try some of their products to verify their ability to produce power while still being quiet enough to pass noise restrictions at certain dragstrips.

We settled on a set of 4.5" in - 4.5" out series 50 mufflers with a 4.5" turn out after the mufflers.

On our first pass with the mufflers we ran a 7.91 second ET @ 175 MPH at Norwalk Raceway Park. That ET corrected to sea level would have been 7.75 seconds. It has been documented.

Look up the Flowmaster 7 Second Club.

They also have a Flowmaster 6 Second Club.

 

It's 2014. A lot of things have changed, but unfortunately Flowmasters haven't.

[MikeStang 247]

They may work very well for that application and its good to know we have members here with your kind of exp.

Maybe I should amend my statement and Say that for a street application with an exhaust size of 3" and LESS the Flowmasters fall short on flow when compared to Borla, Spintech, Dynomax and a host of others. and are louder to boot and cost a bit more.

HOWEVER if you are going for 3" and above exhaust they may be a viable alternative for you :)

[prayers1 153]

I have a set of Sanderson shorty headers, 2 1/2" pipe to an H then to Flowmaster 40's. then out the back. The drone is a little louder then I expected. My wife hates it. As for sound I'm not that impressed, but since they are welded on I have to leave it for now.

My 2 cents.

[MikeStang 247]

cut them bad boys off and weld ya some more on there Prayers.

I just fitted mine with Borla Pro XS and turn downs...have to take car out of shop to see how loud it really is going to be.

[MikeStang 247]

All Home built... I bought some 2.5" radius bends and one piece of 8' long straight pipe from the muffler shop...mufflers are used off of the neighbors car next door who said they were too quiet...I told him he needed a real motor to make them sound off haha. Total Cost $150.00 in material and a gas refill on my Mig bottle 55.00 ==== $205 Total

[MikeStang 247]

If the mufflers were installed in this configuration you could install 18" long mufflers no problem.

The end of my turn downs falls about an inch short of the axle

[Kaspar 21]

I see, but don't you want the fumes and sound out after the rear bumper or is it not a problem, that it ends before the car ends?

[BuckeyeDemon 211]

I see, but don't you want the fumes and sound out after the rear bumper or is it not a problem, that it ends before the car ends?

 

dumps as you describe open the opportunity for fumes and extra sound reverbing to the cabin. the only reasons i can think of to do that on a street car is to reduce the cost of the exhaust system or routing to the very back is impossible due to rear suspension choice.

[69cat&stang 10]

sportsroof69, can you please post the actual data showing the power loss using flowmasters? i've looked and i can't find anything besides a company comparing themselves to flowmaster and even then the power was either the same or within a horsepower one way or another. Not doubting you but i'd be very interested in seeing that and i'm sure others would be as well. Still like the sound of the flowmasters over anything else thou, JMO

[MikeStang 247]

It's a FLOW comparison not a power loss comparison.

I'll see if I can dig up the CD and paper work

[MikeStang 247]

And yeah I need to get the exhaust out the rear of the car, just gotta figure out what tips I'm gonna use because my valance doesn't have cut outs for tips

[1969vert 55]

I have Hushpower 5"x 20" under my car keeping my 427 quiet..they are at a angle and dumps..No drone here..

[Kaspar 21]

Is there a '69-valance that has a cut-out for the exhaust tip? I've only seen it on older models.

[BuckeyeDemon 211]

Is there a '69-valance that has a cut-out for the exhaust tip? I've only seen it on older models.

 

the mach 1's had a cutout.

[Brian Conway 264]

69 rear valance with exhaust cut out. Brian