Stock mufflers... How restrictive?

94GT40 · Apr 8, 2005

Here's the deal...

I'm going to get a custom fabricated X-pipe with no cats. I'm retaining the 2 1/4" stock exhaust. I want my car to sound nice, not too loud, expecially at cruising speed, but I also don't want to restrict flow with my new combo. It will be the following:

GT-40P heads
1.7 roller rockers
Cobra intake
65mm throttle body
Shorty headers

I was going to go with the Dynomax turbo mufflers, but the guy at the exhaust shop suggested that I just stay with the stock mufflers. He says that any chamber mufflers are going to be too loud, and any turbo style mufflers are going to be just as restrictive as the stock mufflers.

How do the stock mufflers compare with other aftermarket mufflers regarding flow rates.

PS: He says that I will like the sound with no cats, x-pipe and the stock mufflers.

Any help, suggestions?

RIO5.0 · Apr 8, 2005

I still run my stock muffs...they're the original 56k ones...I run LTs with a Prochamber with the stock tails and it sounds good, with the H/C and LTs the motor takes on a better tone anyway......I have some 2.5 tails I bought this Winter to throw on it to bring it up a tad ....
I ran Spintech Sportsmans also...When I get tired of the noise, I swap the stockers back on...

If I was you I would be looking for something along the lines of the newer Cobra, Mach1,Bullit mufflers...They are less restrictive than our 95 yr muffs...I have read articles stating they actually flow damn good...The Y2K Cobra Rs are a nice flowing yet quiet muff also...they cost a freakin fortune tho...I search the classifieds/Ebay looking for one of the above for mine...

CManT1914 · Apr 8, 2005

Well considering you don't gain any HP with new mufflers (maybe 1 or so), then I'd say they aren't very restrictive at all.

94GT40 · Apr 8, 2005

CManT1914 said:
Well considering you don't gain any HP with new mufflers (maybe 1 or so), then I'd say they aren't very restrictive at all.

I didn't really think of it that way, except for the fact that if you open up the rest of the engine, mufflers may become a larger restriction than they are on a stock engine.

94GT40 · Apr 8, 2005

Anybody know what the stock mufflers flow?

GRGT1994 · Apr 8, 2005

94GT40 said:
Anybody know what the stock mufflers flow?

exhaust.

SuperDust22 · Apr 8, 2005

RIO5.0 said:
I still run my stock muffs...they're the original 56k ones...I run LTs with a Prochamber with the stock tails and it sounds good, with the H/C and LTs the motor takes on a better tone anyway......I have some 2.5 tails I bought this Winter to throw on it to bring it up a tad ....
I ran Spintech Sportsmans also...When I get tired of the noise, I swap the stockers back on...

If I was you I would be looking for something along the lines of the newer Cobra, Mach1,Bullit mufflers...They are less restrictive than our 95 yr muffs...I have read articles stating they actually flow damn good...The Y2K Cobra Rs are a nice flowing yet quiet muff also...they cost a freakin fortune tho...I search the classifieds/Ebay looking for one of the above for mine...

How do you like your spintechs, you have any sound clips?

Dustin

RIO5.0 · Apr 8, 2005

No sound clips.....I like the sound...sometimes the noise kinda wears on me and I like quieter...so I swap...The stock muffs have a nice tone to em...having 56k on em don't hurt either...

final5-0 · Apr 8, 2005

I still got mine. The complete catback as a matter of fact.

After I put the larger heads and stuff on the car they got a good bit louder, lol.

Later
Grady

JJ95GTID · Apr 8, 2005

GRGT1994 said:
exhaust.

Every forum has one.

final5-0 · Apr 8, 2005

A good while back a guy who used to post on this forum had a full tilt 347 stroker who switched from the stock catback and only gained 10rwhp.

A milder combo would not benefit as much due to the reduced aif flow.

Bottom line is ...... catbacks are a terrible gain for the buck spent

Later
Grady

94GT40 · Apr 9, 2005

final5-0 said:
A good while back a guy who used to post on this forum had a full tilt 347 stroker who switched from the stock catback and only gained 10rwhp.

A milder combo would not benefit as much due to the reduced aif flow.

Bottom line is ...... catbacks are a terrible gain for the buck spent

Later
Grady

Thanks Grady... So what you're saying is that I might only be losing maybe 4 hp for the sake of my sanity?

Due to the whole concept of my Mustang build-up, a low budget all around street performance car, I have been trying to cut through the BS on most performance parts. [IE: Spend money only on stuff that really gives you the most bang for the buck.] I had already decided to keep the stock exhaust piping, with the exception of the cats, and *maybe* go with different mufflers.

I didn't think that at the level of performance I'm after [300fwhp] that the 2 1/4" piping will be much of a restriction. Besides I kinda like the stock exhaust tips, especially when you polish them up a bit.

PS: The guy at the exhaust shop told me that the stock mufflers were stainless. Is that correct?

GRGT1994 · Apr 9, 2005

94GT40 said:
The guy at the exhaust shop told me that the stock mufflers were stainless. Is that correct?

Don't know, but based on the surface rust on my stock pipes and mufflers, I'd be surprised. I don't think stainless corodes like that.

final5-0 · Apr 9, 2005

94GT40 said:
Thanks Grady... So what you're saying is that I might only be losing maybe 4 hp for the sake of my sanity?

Due to the whole concept of my Mustang build-up, a low budget all around street performance car, I have been trying to cut through the BS on most performance parts. [IE: Spend money only on stuff that really gives you the most bang for the buck.] I had already decided to keep the stock exhaust piping, with the exception of the cats, and *maybe* go with different mufflers.

I didn't think that at the level of performance I'm after [300fwhp] that the 2 1/4" piping will be much of a restriction. Besides I kinda like the stock exhaust tips, especially when you polish them up a bit.

PS: The guy at the exhaust shop told me that the stock mufflers were stainless. Is that correct?

Mark

Yes, the original Ford catback is stainless.

As you see in my sig I almost made it to the 300rwhp mark with the stock catback, as well as the stock tb & maf. I am legal with the Mac h-pipe so it does cost me a few hp but I gotta pass a strict dyno roller type emission test each year so it is nice to have no probs when that time comes.

You can see that I too went for the most performance bang for the buck.

As for the cats I've seen some of the guys who go to the track often say an off road mid pipe gave them a about tenth and one mile faster. That would be about 10 to 15 FWHP so IMHO, they are the biggest hold back in the complete original stock exhaust system.

Something I've not shared with anyone on this forum is that the stock exhaust manifolds are not as restrictive as you might think. Me and some of my gearhead buds were talking a good while back about my car. We compared our old school combos to my 95 and we quickly saw that the gain form exhaust manifolds to headers on our older cars was a good bit more than on the Stangs of today. If you compare the two manifolds you will see those of today are much better flowing.

I've been looking at the stainless Edelbrock catback for my 95 but my guess for the gain it will yield will be less than 10rwhp. Don't know when I'll get around to replacing the last stock part of my combo cause I'd kinda like to get to the dyno to see what the larger tb/maf has gained before the catback.

Later
Grady

GRGT1994 · Apr 9, 2005

final5-0 said:
Something I've not shared with anyone on this forum is that the stock exhaust manifolds are not as restrictive as you might think. . .

OK, I can be kinda thick-headed sometimes so humor me on this one. I thought the stock exhaust was headers, not manifolds. Manifolds are cast pieces, while headers are made of tubing.

dstanggt50 · Apr 9, 2005

I've always thought that for the money a catback costs, you can buy other stuff to give you more power, but when I bought my car it came with what looks like flowmasters welded to the pipes. But sometimes in mags you'll see them give around 5rwhp or so , I think I would still spend the money elsewhere.

final5-0 · Apr 9, 2005

GRGT1994 said:
OK, I can be kinda thick-headed sometimes so humor me on this one. I thought the stock exhaust was headers, not manifolds. Manifolds are cast pieces, while headers are made of tubing.

Yes, I guess you are correct. I've been at this stuff for so long I just call them that out of habit.

You have to be careful when talking to old farts like me, lol.

Later
Grady

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