2.25 exhaust for noise control. Cat back or just tailpipes?

[bcmbcmbcm]

Hi folks,

I have a basically stock 5.0 (306 now, balanced, but stock H/C/I), with a 2.5 magnaflow cat pipe and a 2.5 dynomax cat back system. I want to quiet it down a bit...I was thinking of changing the tailpipes to 2.25, or, changing the whole cat back system to 2.25. Cost isn't an issue...I just want it to be right. Please let me know your thoughts.

Brett

 

[2000xp8]

I doubt the pipe size itself is going to change the sound much.
Put a stock h pipe back on, that should knock the sound down, having the stock cats is like having 4 little mufflers.

 

[Gearbanger 101]

Swap out the Magnaflow mufflers with a set of Dynomax Super Turbo's.....call it a day.

 

[MFE92]

Or Dynomax VT's. Pretty quiet until you get on it and their internal bypass valves open up. Here's video of them on my mustang, with the microphone under the console directly below the armrest. These are dumped ahead of the axle FWIW.

 

[Gearbanger 101]

Or Dynomax VT's. Pretty quiet until you get on it and their internal bypass valves open up. Here's video of them on my mustang, with the microphone under the console directly below the armrest. These are dumped ahead of the axle FWIW.

I'd thought about the VT's for myself, but couldn't seem to find anyone who had them on the Fox? I dig the quiet cruise, but how do they control exhaust drone? Haven't found an aftermarket muffler yet that's been able to eliminate the interior drone between 1,800-2,300RPM like the stockers do?

 

[MFE92]

That's the reason I bought them, because I have no real room for 1/4-wave drone canceller tubes under the car thanks to the suspension. The VT's knock it down very well, I'd go out on a limb and call it eliminated.

 

[Gearbanger 101]

Interesting....and what's a pair of them running $ now a days?

Got a feeling my BBK Long Tubes, Off Road-H and my current Raven (Flowmaster knock offs) are going to be ear splitting when I get them on. Wouldn't mind quieting them down....a lot!

 

[MFE92]

$85 a piece for 17159's on Amazon, that's $15-20 cheaper than SummiJegs

 

[gearheadboy]

Sounds good. It may need a .25oz weight on the left rear wheel to be perfect but it sounds real good.

 

[boostfrk]

Agreed that the reduced pipe diameter won't help much. I have Dynomax Super Turbo's with an O/R h-pipe and it's louder than I'd like at times, but, it's a lot quieter than Magnaflows.

 

[FoxMustangLvr]

I must be the only one that likes it LOUD! No music in my car except the 8 cylinders singing sweet songs through the o/r H to dual Flows and the volume control under my right foot

btw, like other said CATS and mufflers are what increase or decrease the sound your car makes.

 

[Gearbanger 101]

I must be the only one that likes it LOUD! No music in my car except the 8 cylinders singing sweet songs through the o/r H to dual Flows and the volume control under my right foot

btw, like other said CATS and mufflers are what increase or decrease the sound your car makes.

A healthy exhaust note, I like. Interior resonance that rattles your teeth loose when cruising, I do not. I had a Mac system on my last mustang with an O/R mid pipe and I was hearing it in my sleep. Loud exhaust systems get old fast.

 

[FoxMustangLvr]

My 5.0 is a weekend cruiser during summer time only (since it freezes/snows out here all winter). I guess for me I don't do long enough nor consistent enough driving to rattle my eyes enough to the point I feel it needs to be taken down a notch or two.

To each is their own.

 

[bcmbcmbcm]

hi everyone, thanks for the replies. I wasn't sure if I made it clear but I am running Dynomax super Turbos already. I love the note but the decibles are a tad too high and I do have some drone. After years of changing exhaust systems to bigger tubing I have read that smaller tubing reduces noise and drone. I have also read that exhaust velocity slows as it moves down the system (and cools), so it is ok to step it down a little further down the system. But this is all theory....I have never done it! I do know the stock 5.0 exhaust was 2.25....but I really don't want 4 cats, even if I could find them.

 

[ratio411]

hi everyone, thanks for the replies. I wasn't sure if I made it clear but I am running Dynomax super Turbos already. I love the note but the decibles are a tad too high and I do have some drone. After years of changing exhaust systems to bigger tubing I have read that smaller tubing reduces noise and drone. I have also read that exhaust velocity slows as it moves down the system (and cools), so it is ok to step it down a little further down the system. But this is all theory....I have never done it! I do know the stock 5.0 exhaust was 2.25....but I really don't want 4 cats, even if I could find them.

Generally speaking, an H-pipe is quieter than an X-pipe, larger pipes are quieter than smaller pipes (sound volume-wise, larger tubes have more 'deep' sounds that rattle and drone), and of course cats will smooth and quiet the exhaust.

You are correct though, that as the exhaust gasses move back from the engine, they cool and shrink in volume, meaning a smaller pipe can be used to carry the same volume of exhaust gas.

 

[1200gt]

I have been following the same train of thought as the poster, BCM. I have heard tons of ponies over the years and have come to know almost all of the suptle differences between the various combinations of exhaust, for the Fox at least.

I have decided to go back to the stock 2.25 tailpipes, as I find those coupled to flowmasters (40's) are desired by my ears. Too quiet and it's just no more fun. Too much drone, and it's just no more fun. I think we all come to a place in our stang evolution where we get over the full out rumble sound and want to settle into a sound that is just below the sound of a "Street Race About to Happen."

BTW, I am still looking to buy a good set of stock 2.25" tailpipes for my 86GT. LMK what you have. Funny, everyone I know took them off their cars but no one seems to come online to sell them...????

 

[bcmbcmbcm]

Hi folks,

I have decided to try the 2.25 tail pipes. But where should I reduce the system from 2.5 to 2.25? Behind the Mufflers? Behind the cat pipe? In front of the mufflers? The price between complete cat back systems and just the pipes isn’t that great, but I don’t want to do this twice. I read that exhaust is turbulent right as it exits the muffler and this is a good place to reduce it. Anyways what are your thoughts? (The entire system is currently 2.5.)

Thanks,
Brett

 

[1200gt]

Hi folks,

I have decided to try the 2.25 tail pipes. But where should I reduce the system from 2.5 to 2.25? Behind the Mufflers? Behind the cat pipe? In front of the mufflers? The price between complete cat back systems and just the pipes isn’t that great, but I don’t want to do this twice. I read that exhaust is turbulent right as it exits the muffler and this is a good place to reduce it. Anyways what are your thoughts? (The entire system is currently 2.5.)

Thanks,
Brett

Brett, I'd go for reduction at the tailpipes just behind the mufflers if you have fairly new Muffs. If not, and you do not nor plan to build a mod motor, then start after the Cats. Most folks just thru on a set of mufflers anyway and didn't change the cats. That would put you back to stock dia.

The sound of drone is usually somewhat contained once a little back-pressure in induced at the tailpipes as the exhaust is recompressing going from 2.5 to 2,25 - kinda like a blow nozzle... Others, will want to straighten this idea out more clearly.

Where do you plan to get the TAILPIPES? I've been looking for an OEM set forever. No one have come thru for me with a nice set of take-offs. How about guys, who has a set of 2.25's laying around? Me and Brett are probably the only two Stangers that want to put 2.25" pipes back on; that mean ther should be about: 3 or 4 Hundred Thousand sets out there somewhere

 

[1200gt]

Or Dynomax VT's. Pretty quiet until you get on it and their internal bypass valves open up. Here's video of them on my mustang, with the microphone under the console directly below the armrest. These are dumped ahead of the axle FWIW.

Dude! They sound sweat! I have Flowmasters dumped in the same location and they sound like a Track-War about to break out. Those VT's are so much smoother.

That's the thing about Mustang exhaust, I want all of the sounds! I guess I'm just a Stang NUT.

 

[2000xp8]

Hi folks,

I have decided to try the 2.25 tail pipes. But where should I reduce the system from 2.5 to 2.25? Behind the Mufflers? Behind the cat pipe? In front of the mufflers? The price between complete cat back systems and just the pipes isn’t that great, but I don’t want to do this twice. I read that exhaust is turbulent right as it exits the muffler and this is a good place to reduce it. Anyways what are your thoughts? (The entire system is currently 2.5.)

Thanks,
Brett

Brett, it's not going to work.
When i bought my car it had 3 chamber flowmasters welded in stock catback and a stock h pipe. It was fairly quiet especially compared to everyone elses cars that were catless.
I found a 2.25 offroad h at the junkyard for $50 and installed it.

It was loud catless, and no different than when i put a real 3 chamber 2.5 inch catback on a few years later.

A 1/4 of an inch pipe size will make no change.
Either change the mufflers or add cats.