1984 3.2 header/exhaust
 

I have searched and read many threads but would still like to ask the question before spending the money.

I want to add an exhaust to my car mainly for the visceral improvement. Nothing crazy loud just want to hear it some. Saying this I am strongly considering doing headers and exhaust while I doing it for a better sound and hopefully a decent power increase. I believe I have narrowed down to M&K headers with heat and muffler.

The million dollar question ($5000 actually) is why shouldn't I go this route? Is it money well spent? Looking for constructive/helpful opinions and experiences.

Thanks
Foster

I've been there, done that. I currently have headers and a custom muffler setup. I only did it because I was able to trade my stock exhaust straight across for this. I still spent money on the install and changing the muffler setup twice. If I had to shell out any money, I wouldn't do it again.

For the best bang for your buck I'd recommend a cat bypass and some sort of sport muffler. You'll retain the best heat and never have any drone.

Appreciate your real world experience Mr. Merk.

Thanks

I went down this path myself the last few months (Infact, have actually spoken to "Mr. Merk")...1986 3.2 here and I was looking at a simple refreshing of the engine and new exhaust. I actually had the 3.2 SSI's nearly ordered along with a 2in2out muffler. I talked to quite a few people and a few (what I would consider) experts/trusted sources and most stated for me to keep the factory exchangers and run a bypass along with a sport muffler of some sort.

Fast forward and now my 3.2 is going to be a 3.4 and the money I saved from new headers/exchangers and exhaust went into the engine and new parts. Basically, my 4-6 grand for new exhaust went to new pistons and cylinders...

Anyway, point is I needed the heat here in the midwest and to my surprise a lot of folks said to just keep the original exchangers, run a bypass and sportier muffler - that was with a stock 3.2 before the 3.4 build.

Call some of the exhaust pros from the forums, they were extremely patient and helpful.

EDIT: I will still run a bypass and sport exhaust with the 3.4 build. That may change as things progress, but for now I am keeping it simple exhaust wise.



Erik

This is well-researched turf, and you'll benefit greatly from talking to folks who've done it a thousand times, like Brian Bodart of M&K. Don't just buy stuff without talking to him (or folks like him) first. The right answer will depend on your goals and your car's other mods (if any).

I have an '85 3.2 that I'm keeping to an OEM+ level of restomods, no more. So, I went with the M&K "active exhaust" catalytic converter swap and the MKM33 1-in-1 out muffler. Throttle response definitely improved by swapping out the original cat to the active one. The MKM33 muffler doesn't drone at all and the combination sounds great -- nice and deep tone but not too loud. You can still hear the characteristic fan whir of an aircooled 911. Brian was very responsive by both phone and text when I had questions. Super happy customer here.

I have a set of George's headers and a custom muffler made by Ben McFarland of original M&K fame on my 3.2 with a matched Sal Carseller chip. No heat. Significant seat of the pants power increase with the system. I would like some heat but have been driving for 3 years like this. i think there are new electrical heaters on the market, I might look into those. Very happy with the raw sound and power bump. It's not for everyone. I don't have a radio.

Only sound clip I have

<iframe width="1219" height="686" src="https://www.youtube.com/embed/wpRYJ7C-y0s" title="M491 Goodness" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

Shaun, that sounds great!

I have spoke (via email) with Brian @ M&K. As stated above he has been very responsive and helpful. Still wanted to hear others opinions/experiences and appreciate all the comments above.

I don't really want to spend the money to go the header route, but also don't want to not go all in if the results are dramatically better, to later decide to switch to headers and have to purchase another exhaust.

Thanks again for the input.
Foster

The biggest change when going to a different muffled exhaust is going to be in the noise arena.

headers are great at making hp over a relatively narrow rpm range when
TDC compression cam overlap is increased
no muffler is installed
tapered post collector pipes are used, reverse cone added at the end spreads the torque out a bit


stock air cooled 911 cams from '74 up have little to no TDC overlap
stock mufflers are better at reducing noise than increasing flow, Mufflers are a balancing act between noise and flow, increase of one almost always reduces the other, this can be mitigated by a larger internal muffler volume and flow geometry.

Steve W, probably has more experience w/ different exhaust designs due to his chip tuning business. Check out the different setups on his site, as you will want one of his chips for a Motronic 911

I agree that w/o a lot of other internal mods a stock 3.2 exhaust, sans cat or w/ a high flow cat if necessary, and a well chosen muffler that you like sound wise, is the best way to go.

I worked with Brian B @ M&K a few years back. Very positive experience, craftsmanship is above and beyond what I'm used to from the world of aftermarket parts. I settled on a GT3 muffler for my build, M&K built long tubes with heat, and fitment is absolutely on point...

You'll be spending money. Do the thing you want to do all the way and be happy with the result!

Headers, sport muffler and a chip made a huge difference on my 3.2 when it was normally aspirated. It really woke up the car.

I forgot to say that my muffler is doing absolutely no muffling. It's basically a pair of megaphones with a big cylinder acting as a mounting crossbar.

I love it when folks throw around expressions like this

What exactly was the huge difference??

dynos over and over show net gains of 12-20 hp when going to even race headers on a chipped but otherwise stock 3.2, usually closer to the 12 than the 20, there is a huge overlap in that data set w/ the data set of setups using stock exhaust w/o cat or w/ a sport cat and some sort of muffler.

in other words most of the gains are coming from chip and cat changes not from the actual piping changes.

Thanks again for the inputs.

I think I will go with the premuffler and exhaust. Maybe the active exhaust version.

Appreciate you all.

Foster

Semantics. I never said headers alone made a huge difference. I clearly mentioned headers, muffler, and a chip as a combined setup from my personal experience. That's what transformed the car. My comment wasn’t about isolated dyno numbers. It was about the overall improvement in performance.

There are perceived gains and quantifiable gains.
For example, when converting a stock CIS engine to Webers it feels like 50hp but on paper (dyno) it is only 10hp. The improvement of throttle response, the feel of extra torque and the sounds are not captured on dyno sheets. Same goes for headers. You're not going to get that screaming banshee tuned sound out of the OE heat exchangers. The bump in torque/HP doesn't look like much on paper but it is a 10% increase which is quite noticeable. Yes you can get that same 10% bump on the 3.2L with OE heat exchangers by adding a pre-muffler and chip. Adding the chip to tuned headers and the bump is 17% over stock. As with most things there are diminishing returns as the normally aspirated engine gets closer to 100% volumetric efficiency.

This is the difference:

https://youtu.be/hNnNlFDDmBE

That’s true—the sound is something I really struggle with. My car used to have a fantastic raspy tone with a cat bypass and a Dynomax muffler. It sounded great all the time, even at idle.

The headers just don’t have the same presence, in my opinion. But at full tilt, right in that high-RPM sweet spot—they absolutely scream. It’s pure nirvana.

I'm the third car, lagging behind but sounding the most

https://www.instagram.com/reel/CyOekR4LZxc/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA==

w/o cam overlap and open exhaust the only thing headers provide in increased flow,

w/ smog cams and muffled it' all about flow, remove the flow restrictions, chip tune and there is little to no difference, the 2 choke points stock are cat and muffler.

the chief difference between a RoW 3.2 w/ 231hp and a US 3.2 w/ 207hp is a cat and a chip, the mufflers are the same , a few more hp are possible(but not surely) be added w/ a good free flowing muffler. More likely just a few more dB .


Mufflers are what provides the aural quantity and quality and what each of us is willing to put up w/ is very different

on my 911 I've had 3 different header set ups and 1/2 a dozen different mufflers over the past 49 yrs,

what I've learned is that w/ a stockish engine it's all about flow for power and a good muffler can provide that

for noise it's all about how the muffler handles the flow, a good one can be quiet and have good flow, a bad one can have poor flow and make a lot of noise, and there are many in between

a nice compromise is valved flow as can be implemented w/ a GT3 muffler, which has great flow and is reasonably quiet, but will still be too loud for some .

This is the way.

I've tried A LOT of pre-mufflers / active pre-muffler / stock mufflers / modified stock muffler / sport mufflers / stock heat exchanger and header permutations. 1 in / 1 out and 2 in / 1 out.


I went from this...

http://forums.pelicanparts.com/uploa...1745762598.jpg

To this...

http://forums.pelicanparts.com/uploa...1745762682.jpg

...in the name of extracting every last HP out of a 3.4 liter, single plug, 964 cam, Motronic build AND looking for a particular sound. It's a VERY expensive last mile / step.

Everyone's Price / Value / Happiness matrix is different, but for my $, as a general rule of thumb, I'd stick with stock HEs and some combination of cat bypass / resonated / active pre-muffler + sport muffler on anything up to a 3.4 liter single plug Motronic motor and reserve the header / two-in muffler setups for 3.5 liter+, twin plug, non-Motronic motors.

Frank,
Did you ever do dyno runs to confirm the improvement of each upgrade?

I chose Fabspeed RSR package with heat. No regrets, definitely altered my experience and car's character. Noise is in pleasing to me.

http://forums.pelicanparts.com/uploa...1745796202.jpg


http://forums.pelicanparts.com/uploa...1745796652.jpg

Each one? Every permutation? No. I'd need someone to start a very successful Go Fund Me page for all the dyno runs that would have taken.

No, I could only afford two...

1988 3.2 with open air box lid, Web 20/21 cams, stock HEs, Dansk pre-muffler and a Dansk 1 in / 1 out 84mm sport muffler...

http://forums.pelicanparts.com/uploa...1744205374.jpg

1987 3.4 with open air box, 964 cams, 10:1 CR, M&K longtube headers and M&K 2 in / 1 out muffler...

http://forums.pelicanparts.com/uploa...1744205215.jpg


I tried to use the same dyno for both cars, but the first dyno was no longer available.

What were the results, Frank?

The results were... Good.

I kid, I kid. Here you be, including links to the photo galleries for Easter eggs and some vids of the pulls...


https://amoroso.smugmug.com/1988-Porsche-911-M491-M470-Poi/1988-911-Dyno-tune-at-Game

*BTW, I wouldn’t put any stock into this “before” pull as the car had a 24 pin ECU with a chip of unknown provenance in it. Steve swapped it out for a 28 pin ECU with custom programming based on nine additional dyno pulls.

http://forums.pelicanparts.com/uploa...1745873853.jpg



https://amoroso.smugmug.com/1987-Porsche-911-M491-M470-Gemini-/Steve-Wong--Ed-Pink-dyno-tuning-21623

http://forums.pelicanparts.com/uploa...1745873871.jpg


Shame the tests couldn't have been done on the same dyno.

Spoke with Eric Williams at Air|Water on Saturday about his / Bursch's newest offering for those that don't want to incur the expense of a GT3 rear muffler system...

Looks intriguing. Then again, I'm intrigued by a lot of different mufflers.

http://forums.pelicanparts.com/uploa...1745876257.jpg

It's an awful design
http://forums.pelicanparts.com/uploa...1745885023.jpg

the turbulence created where the star is destroys flow

here is what the flow looks like for an SC or Carrera 3.2 w/ separated sides
http://forums.pelicanparts.com/uploa...1745885116.gif

Interesting. What's the effect of the valved outlet when closed then?

The X pipe is the problem here, which Bill has covered many times over. I believe the vacuum operated valve is just for drone control as it keeps the passenger side outlet closed until WOT

I know nothing about mufflers but that caught my eye, directonal air being pushed into opposite directional air.

Why would a known exhaust manufacturer do this? Are there any benefits at all?

It might help the sound a bit, but probably hurts performance. These setups became popular with odd-firing V8s, and I think a lot of people just assume the same logic applies to any dual-exhaust engine. But like Bill pointed out, even-fire engines don’t really benefit from it. If you look at Porsche’s naturally aspirated race cars — at least the ones I’ve seen — they never merge the exhaust, which says a lot.

on a GT3 muffler?
http://forums.pelicanparts.com/uploa...1745947068.jpg

the upper, red, is the quiet pipe it exits into the large central chamber where the gases expand and are routed to the exit, blue.

The lower inlet is the loud pipe, black flow,

here there is a properly designed x over between the 2 exits, The sole purpose of the xover is sound tailoring and attenuation.

correct, that was my theory too. odd fires do need the crossover, but even there care needs to be taken to merge the 2 flows, unless a bundle of snakes exhaust is used where 1 left and 1 right cross to the other side collector

http://forums.pelicanparts.com/uploa...1745948128.jpg
http://forums.pelicanparts.com/uploa...1745948128.jpg
http://forums.pelicanparts.com/uploa...1745948306.jpg

no even fire engine need ta cross over and if used it's solely to expand the acoustic volume for nise purposes

if a x-over is used on an even fire engine then care is still taken to smoothly merge the 2 sides as on this Cox design

http://forums.pelicanparts.com/uploa...1745948306.jpg
http://forums.pelicanparts.com/uploa...1745948306.jpg

If a x-ober like the Bursch is used it's best to just have a glancing blow where the 2 sided connect and there have only a relatively small opening

sort of like this
https://cdn11.bigcommerce.com/s-fh9w...899480.jpg?c=2

"Glancing blow" Nice.

Thanks for the explanation.

May explain why Car Bone opted to not crossover their muffler flow...

http://forums.pelicanparts.com/uploa...1745950572.jpg


https://www.carbone.pl/en/products/carbone-active-bypass-muffler-gtu_07-5051


There are SO MANY muffler options nowadays, including valved / active configurations. It's an embarrassment of riches. Oh how I'd love to dyno them all back to back to back to...

For street use where sound quality & quantity is likely to be far more important than the last few hp the best muffler I've ever had is the Fabspeed RSR, no highs, quite enough to hear the cooling fan, nice basso burble everywhere, no resonance.

I haven't dynoed mine yet but the car is far livelier, not really an apple to apple comparison as I also resealed the engine.

Here's a utube in my garage
993 engine in "76 Carrera 3.0 chassis w/ Fabspeed RSR exhaust

Love the sound of the sound of that! Especially for my more wife-friendly cars. Agree on sound quantity and quality being more important on street cars.

For hot rod, I still like the GT3 muffler. No subtlety there. There's no hiding throttle position & load there. Everyone knows what the drivers right foot is doing. My experience is with that on a 3.5 liter, dual plug, MoTec motor. It has sound quantity and quality and it may well have every last horsepower too. ;-)


Interesting that Fabspeed seems to offer an X-piped muffler option too...

http://forums.pelicanparts.com/uploa...1745968735.jpg

Yes the Fabspeed w/t he x has cats, which introduce their own own issues, the x is an ok design if you have to have one

I had a Ti GT3 for a summer it was ok, but much louder than the RSR and performance elt the same open or closed.

I think that the gt3 is much more efficient w/ a 3.8 or 4.0, when I drive a buddies 4.0 Rothsport w/ Motec triggered GT3 at WGi it's eye opening, compared to my 993 3.8 RS

but around town, not so much, and the GT3 is louder, they have issues at LRP noise, stock

Was the GT3 louder than the RSR on the "quiet" setting too? What was the "quality" (low tone, high tone, raspy, etc) of the GT3 in your experience? I know it will differ on different motors.

My 3.4 is generally raspier than I would like, regardless of the eight (or was it nine?) mufflers that I've tried (if you can count the Bisimoto Pulse Chamber as a "muffler") so far.

yes, similar quality just louder w/ GT3, I hesitate to bring in the Rothsport motor as it has far more cam than either my 3.8 RS or 3.6 hotrod