1-in 1-out vs 1-in 2-out

[hymlopez]

Other than the obvious, i.e. looks, what's the difference between a 1-in 1-out muffler vs. the 1-in 2-out one? My 87 Carrera has the first and I always likes the looks of the 2-out, but don't know what could change, I'm guessing sound?

[Oh Haha]

Typically, a 2 out muffler will be louder and may even cause some issues with drone at certain RPMs.

[dw1]

Marginal increase in HP and big increase in loudness.

It changes the nature of the driving experience, especially at mid to high rpm. Not because of the virtually undetectable additional hp, but because of the uncomfortable loudness.

As has been stated, some of them also produce an irritating drone at certain rpms.

I have a Fabspeed euro premuffler and a Dansk 1-in-2-out with 84mm outlets (and a Steve Wong 93 octane chip) in my '87 3.2, and I like the quality of the almost muscle-car like idle and low rpm sound, but it is just too loud at highway speeds.

[Craig T]

Originally Posted by dw1

Marginal increase in HP and big increase in loudness.

It changes the nature of the driving experience, especially at mid to high rpm. Not because of the virtually undetectable additional hp, but because of the uncomfortable loudness.

I have a Fabspeed euro premuffler and a Dansk 1-in-2-out with 84mm outlets (and a Steve Wong 93 octane chip) in my '87 3.2, and I like the quality of the almost muscle-car like idle and low rpm sound, but it is just too loud at highway speeds.

"Uncomfortable loudness"...There's no such thing!

...And the HP produced with a less restrictive exhaust is more than marginal. 3.2's may produce a little more torque at low RPM with a little back pressure, but a more open exhaust will far outperforms a 2-in-1 or 1-in-1-out style muffler...and the torque gain goes away if the exhaust is restrictive beyond a certain point. I just went through an expensive series of dyno runs with various mufflers. The performance difference between them is huge.

[OffCamber00]

I LOVED my M&K 1 in / 2 out.

[Len 911]

If it is to loud then you are too oldl !!!!!!!!! Just kidding I love the sound of my 2 out much deeper sound . I think it sound great

[Craig T]

Originally Posted by len 911

if it is to loud then you are too oldl !!!!!!!!!

lol +1

[hymlopez]

Thanks for the insight guys...I guess my ears are still "young" so I'm going for it!

[KTL]

Yah but hymlopez is asking about the typical stock manifold system with a 2 out stock-like muffler, be it a OEM banana style (Dansk, Leistreitz, etc.), M&K, or whatever suits your taste. Many people share the same opinion that the 2 out stock-like setup can be tiresome after a while.

Craig makes a very good point but his system is configured based on many years of people's custom designs intended to optimize the entire exhaust system, not just slapping on a muffler at the tail end of the system.

[Bill Verburg]

Guys back pressure never increases hp, torque

Just adding a freer flowing exhaust doesn't automatically increase hp or torque either, the engine controls have to be tuned for the exhaust to get any of the benefits

w/a 3.2 a new chip designed for the exhaust is the key to getting the best from the system at wot, the O sensor feedback loop will usually compensate at part throttle but at wot it all depends on the fixed map in the chip

The most common complaint w/ dual exhaust is resonance in the 2krpm range, right where most people drive most of the time, resonance can be tamed by having a large can like the stock banana mufflers or w/ a dual muffler set by using a cross over before the mufflers which spreads the resonance out over both mufflers, the cross over needs to be carefully implemented so as not to create gas turbulence, on a v8 a simple H suffices though as w/ collectors a high incidence angle merge can also be used

[KTL]

Originally Posted by Bill Verburg

w/a 3.2 a new chip designed for the exhaust is the key to getting the best from the system at wot, the O sensor feedback loop will usually compensate at part throttle but at wot it all depends on the fixed map in the chip

Very true words from Bill. Friend of mine I track with for many years got the itch to change his 3.2 Carrera exhaust from stock setup w/no muffler ("track pipe") to headers with a stinger/merge pipe similar to what Craig's got on his hotrod. He's lost some pep/speed due to the engine mapping not being modified to account for the considerable exhaust change. Lap timer doesn't lie. New exhaust, fresh tires, slower lap times, disappointed driver. Looks and sounds fantastic though!

[dw1]

Originally Posted by KTL

Yah but hymlopez is asking about the typical stock manifold system with a 2 out stock-like muffler, be it a OEM banana style (Dansk, Leistreitz, etc.), M&K, or whatever suits your taste. Many people share the same opinion that the 2 out stock-like setup can be tiresome after a while.

Craig makes a very good point but his system is configured based on many years of people's custom designs intended to optimize the entire exhaust system, not just slapping on a muffler at the tail end of the system.

I couldn't agree more. My system has stock manifolds, a euro premuffler and a 2-out with 84mm end pipes.

In terms of performance, one should really go for a full exhaust system including headers. Whether one gets Bursch or another brand, headers and a 2-in-2-out or something along those line of Craig T's system is the way to go to justify the increased loudness with increased performance.

Oh, and a Steve Wong chip will definitely help the engine take advantage of the low-restriction exhaust.

Btw, Is isn't just that my ears are getting old, it's that I really need to avoid getting extra attention for those who "protect and serve"...

[redridge]

any opinions on the M&K 1in 2out(side outlet) vs the 1in 2out gt3 style (center outlet)... is one louder or better performance than the other. Im really interested in the gt3 style... but isnt really reviewed often.

[MMiller]

Not quite the question you are asking as I have 2 in coming off SSI's but I got rid of my Dansk 2 in 2 out because of 2 - 2500K drone. Now run a 2 in 1 out Bursch and think it's great. Makes a nice sound when you want it and very civil when you don't.

regards,

[Arne2]

Originally Posted by redridge

any opinions on the M&K 1in 2out(side outlet) vs the 1in 2out gt3 style (center outlet)... is one louder or better performance than the other. Im really interested in the gt3 style... but isnt really reviewed often.

I've driven a car with the 1-in GT3 style M&K. At the time I drove the car, it had a stock cat on it. I loved the sound, and there was no drone that I could detect. It was, however, rather loud from the outside. Loud enough even at idle that I would be concerned that neighbors might object to my leaving for work at 6:00 AM. Since I drove the car, its owner was in touch with M&K about getting some sort of baffles for the tips to quiet it some. I do not know if that has happened yet, nor how that might change things.

[redridge]

Originally Posted by Arne2

I've driven a car with the 1-in GT3 style M&K. At the time I drove the car, it had a stock cat on it. I loved the sound, and there was no drone that I could detect. It was, however, rather loud from the outside. Loud enough even at idle that I would be concerned that neighbors might object to my leaving for work at 6:00 AM. Since I drove the car, its owner was in touch with M&K about getting some sort of baffles for the tips to quiet it some. I do not know if that has happened yet, nor how that might change things.

thanks, thats what I was afraid of... the kids bedrooms are on top of the garage, would make those early weekend drives kinda hard to sneak out. I dont mind loud, but would hate to piss off the family and neighbors. I had a oem sports exhaust in the 996 that has a button to quiet the exhaust... that setup was priceless.

[Craig T]

Originally Posted by KTL

Very true words from Bill. Friend of mine I track with for many years got the itch to change his 3.2 Carrera exhaust from stock setup w/no muffler ("track pipe") to headers with a stinger/merge pipe similar to what Craig's got on his hotrod. He's lost some pep/speed due to the engine mapping not being modified to account for the considerable exhaust change. Lap timer doesn't lie. New exhaust, fresh tires, slower lap times, disappointed driver. Looks and sounds fantastic though!

Chip mapping is essential to a significant exhaust change on a stock 3.2 motor.

At Aase Motors the dyno runs have shown different 3.2 cars with stock motors can have varied dyno results from the same exhaust system. That's why we usually have Steve Wong in the dyno with us after we make an exhaust change (and I love your company to Steve) Steve can optimize accordingly. I changed to stepped SS headers on my stock 3.2 race car and saw no improvement. At the dyno SW tapped away on his laptop and picked up 12 HP by matching the chip to the new airflow.

Not to kick off another exhaust debate....But , the reality is...No exhaust is the silver bullet for our cars. To maximize performance, the exhaust must be matched to several factors, and not just intake port size, exhaust ports, cam, octane, compression, etc. Even condition and effectiveness of the 3.2 fuel system and remaining stock compression make a difference.

In the Porsche Owner's Club V3 race class (stock 3.2 but otherwise highly modified), guys spend thousands dyno testing different exhaust configurations just to get an extra 5-10HP....And it's usually a trade off...get it at the bottom, or get it at the top. No silver bullet.

[RarlyL8]

Generally speaking, the single inlet mufflers do not drone. Dual inlet mufflers with dual outlets do have a tendancy to drone.
Yes we have several methods to quiet the note for those who prefer a little more stealth than sport.
To optimise the system the entire exhaust must be designed for the engine. Fueling/timing is part of the equasion and must be mapped or adjusted accordingly. That last 5HP costs thousands.

[david.avrahami@]

8 months ago I researched the same topic on the forum and feed back from various experts and concluded that an 1987 Carrera is not really suitable, for a SSI system with a sport muffler. I was more interested in increased torque and mid range hp. (street drive). I opted for a 100 cell SS pre muffler, a 1 in 1 out SS MONTY (Australian free flow Mfg. ) and a Steve Wong chip for this free flow set up.
Amazing performance results, best sound and moderate volume...

[redridge]

Originally Posted by david.avrahami@

8 months ago I researched the same topic on the forum and feed back from various experts and concluded that an 1987 Carrera is not really suitable, for a SSI system with a sport muffler. I was more interested in increased torque and mid range hp. (street drive). I opted for a 100 cell SS pre muffler, a 1 in 1 out SS MONTY (Australian free flow Mfg. ) and a Steve Wong chip for this free flow set up.
Amazing performance results, best sound and moderate volume...

david, can we have more info of your setup... the moderate volume got me interested. TIA