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The A-1 Sidewinder typically uses a MagnaFlo muffler. Mellow & throaty with a nice roar on accelleration. For more aggressive sound, switch out MagnaFlo muffler to Flowmaster.
My $0.02 
Pretty much....
Although the length of the header tubes seems to affect the frequency range of the exhaust note: shorter tubes = higher rap, longer tubes = lower rap, but the tube lengths move your torque band up and down, too.
If you get to Carlisle you can listen to a lot of tubs and when you find one that you like the sound of, ask the owner what muffler they're using. Most won't usually know - they know the system, not necessarily the individual parts (Mine's a sidewinder A1 or mine's a Berg, etc), but in knowing where the system came from you can do a little research and find out the muffler.
I've been toying with the idea of making Pearl Uber-quiet, just for the hell of it, but don't know what that type of muffler(s) would do to my performance. One good way to find out, though.
My exhaust system is a merged header that was shortened. It feeds into a small muffler (brand unknown) that sits beside the valve cover.
The header was on my original car, which predates A-1 sidewinder production.
I'm not sure if I lost any power by shortening the header, but I do know that the little muffler is WAY too loud for me. It's okay, with the top down on the highway, but with the top up, around town, it is painfully loud.
I'm swapping my little muffler out for two larger mufflers that I'll run inline. If I go with the right mufflers there shouldn't be any horsepower loss.
Gordon,
In my hands I don't think my Type1 has seen 4,000RPM, and then only briefly shifting from second into third...What length of header plumbing would be optimum to have my 'torque band' peak at that RPM?
This is the type of sound I would love to replicate. Not sure if a 1915cc motor could do it, but I absolutely love this sound...
takes about 45 seconds in I think before the guy starts the car.
I don't think that guy has a muffler in his system at all.
I agree with Tom; I don't think there's a muffler on there either! Or it's the exhaust with the small chamber right before the outlet.
My Beck Spyder was very similar sounding.... The "muffler" was a totaly hollow glasspack shell of about 16 inch length.... 1915cc engine.... With lean idle jets (.55s) it snapped and had a very angry sound, but would mildly surge at low speed....
Gordon,
In my hands I don't think my Type1 has seen 4,000RPM, and then only briefly shifting from second into third...What length of header plumbing would be optimum to have my 'torque band' peak at that RPM?
The length of the primary tube in a 4-1 exhaust plus the exhaust port length is:
2*L = (ET * v) / (RPM * 6)
or L = (ET * v) / (RPM * 12)
ET is the degrees between the exhaust valve opening and the point you want the low pressure pulse to hit the next cylinder with its open intake valve. I can't tell you what that ideal point is.
v is the speed of sound in the exhaust gas. But this changes with exhaust gas temperature (engine tune). Probably between 1100 and 1900 ft/s.
RPM * 6 converts RPM into degrees/second.
The Length is multiplied by 2 because the pulse has to travel down the pipe, hit the opening, and the low pressure pulse has to travel back up the pipe.
L will be in whatever units you used for v. ft/s -> ft, m/s -> m, etc.
For example, a w110 cam exhaust opens at 55* BBDC and lets estimate I want the pulse to hit at TDC. So ET is 55+180=235. Lets guess v is around 1700 ft/s. At 4000 RPM, L is (235*1700)/(4000*12)= 8.3 ft.
Now you're going to have a tough time fitting 8 ft primaries under the car, but because of harmonics we can divide that number by 2 as many times as needed to make it work at the same RPM, though with less strength each time. So 4.15 ft, 2.07 ft, etc will be ok.
Obviously, finding the "correct" length is going to be quite difficult without a lot of simulation or empirical testing, but even if your estimated length is off 10-15% from "ideal" you'll be fine for a street car (Going from 7 ft to 9ft only changes the peak by ~1000 RPM). Also, any differences in length between the primaries will simply spread the peak out over a wider RPM range, again not a bad thing on the street. Close really is good enough. Even people needing to make headers from scratch usually only care about short vs long and making it fit.
TR, that will be fun for a while, but the noise wears thin very quickly. There are a few of us on this forum who started out with loud exhaust systems and eventually moved to a quieter system. It would be okay if you never put your top up.
Justinh, I've read through your post several times, and even though my head aches I've come to two conclusions:
One...You just made all that up, and are playing with my emotions!
Two...You didn't make it up to prove that some questions lead to deep, inscrutable, and mysterious s**t
What Justin said. Actually, I have no idea what he said. I flunked flank.
I'm not sure what question he's answering. 
Ron,
justinh answered the 40 point question on the M.I.T. PhD exam.
That's exactly the formula I used to set up the tube lengths on my Sidewinder!
I didnt see any thing in that for tube size.witch will also affect it. As will collector type I would think, then there is the 4 into2 into1 systems. or steped systems. but wil all of this, and as many different camshafts how many headers on the shelf are made to work with what......made to fit the car.
Come on Jim!
There are only seven living people in the entire world that understand that formula...and they're all tenured professors.
Question" "Do you knoiw the answer between ignorance and apathy?"
Answer: "I don't know and I don't care."
I wish I understood the whole issue but it's prettu erudite for my pea brain.
Justinh:
I recommend reading Four Stroke Performance Tuning by A. G Bell. There is a copy of the first, second, and third editions of the book on line at:
http://www.filecrop.com/graham-bell-tuning.html
There is a section on exhaust theory that should be required reading. The short version is this: old-school short-primary length merged headers work better over a wider power-band than anybody gives them credit for.
What the world is crying for is a high-quality Type 1 tri-Y like Tangerine Racing builds for Type 4s and 356/912 Porsche engines.
Thanks for posting your formula. I'm 100% in favor of bringing this site into a new era of intelligent conversation, and your post is exactly the kind of resource we could all use.
Justinh, I've read through your post several times, and even though my head aches I've come to two conclusions:
One...You just made all that up, and are playing with my emotions!
Two...You didn't make it up to prove that some questions lead to deep, inscrutable, and mysterious s**t
"It's complicated." wouldn't be nearly as entertaining.
Now ask me why the sky is blue.
what in the He%% happened to my thread! LOL
Typical Speedster.com thread drift. 
what in the He%% happened to my thread! LOL
What Ron said x2! Bwaaaaaa haaaaaaaaa!
You know how guys pretend to be listening when the wife/girlfriend is talking about 'whatever' and their story goes on-and-on with no apparent point or end in sight. Its kinda like that.
BTW - let us know what you decided on your muffler and how it worked out!
Typical Speedster.com thread drift.
so with the proper exhaust you can go drifting??weeeee I havent done this in years!!! weeeee. kinda like flying pigs!!!or pigs on a harly weeeee...
there are somany theroys and concepts.and then comes the race header with a narrow power band. if I had a chassie dyno I would probably do some experamenting on varrying lengths & sizes.but I dont so i will build what I want & what fits the car as I want it to.or just use whats on the car....hmm??I wonder if it even has a header?? if not, it's going stainless... possiably.
Here is Jim Ignacio's A-1.
You know - I think that I have seen that one...that is actually the only one I have seen. I appreciate you putting that on the thread! I like the sound. It still, to me, seems a little more tame for my taste. Out of all the upgrades I could do to my Boxster, I spent the most on my exhaust to make it growl and that is the part I will miss most. Like I said, just looking for ideas for future...but I WILL pounce on something if I hear a noise I cant live without!
what about running two mufflers one after the other? I have heard of some guys on the samba doing that and making the exhaust a lot more quiet. I think I heard them say like 90s honda mufflers were very quiet.
Like some of the others said your going to hear a ton of other noises mixed in including the fan spinning and the inductions noises. You will not appreciate the sounds until its under full load. This video has the camera down low. Jim, any vids of your car under full throttle with no music playing? Also, ask Tiger at A-1 for his oppinions on a more aggressive muffler. The Magnaflows are pretty mellow.
i can atest - the sidewinder / magnaflow / IDF / 2.1L combo sounds pretty bad ass under full load.
it sounds like a handful of coins being flushed down the toilet
what about running two mufflers one after the other? I have heard of some guys on the samba doing that and making the exhaust a lot more quiet. I think I heard them say like 90s honda mufflers were very quiet.
I'm going to do just that-going with inline duals. I haven't figured out what type or brand of muffler to run yet.
add some heat sheilds to that and be sure it is supported real good, remember the heads are held on bu foot long small studs that only torque to about 20 lbsf.and all that stuff is hanging out on the end of them.I have seen head gaskets leek due to illfiting headers.add all the weight & unless it is supported very well at about 4 points you have an recipie for disaster.but if you do it right, you will love your stereo again. the only loud cars I like have slicks on them.
What sounds good to one might not to another.
The sound of the A-1 Magnaflow muffler to my ears was torture. It certainly was loud enough but the pitch, under load, was like fingernails on a chalkboard. I thought it might be the placement of the tip, so I moved it from underneath the car to the side but it didn't help. I added a resonator (bullet muffler) but that just slightly muffled the same pitch.
I finally switched mufflers and put a Flowmaster Hushpower on the system. It's still way loud under load but it's at a pitch that is much more pleasant to my ears and my wife's.
The best sounding to me? Stan Galat's IM. The sound is menacing yet in control, like Jack Reacher. Of course, Stan has all sorts of things going on; huge carbs, straight-cut gears and a Mad Scientist exhaust system that he assembled and has more money in than I have in my car.
Todd, the only way you're going to find the "sound" is either by experiment or by observing a collection of these cars and asking the owner what he's got.
^^^ this is so true, I built a 2387 for a 65 912, with sidewinder and that muffler just wouldent do for me,Im not sure the owner will tollerate it for long, but for some ,yes it's music to thier eyes.....or was that ears? yup guys it has to look good too.
I did have a supertrap on my car for a short while,I hated it,but some love it.apples,banana's oranges,vinilla&chocolattee, were all a bit different ....some more than others !!
Stan is a friend of mine and my mentor when I shopped for my car. His IM is truly something special. I spent a day last June trailing him in my VS on the Corn Daze get together in Peoria, and that is some vehicle. Check the silver car on the far left of the lineup for February 2013 in the calendar, that is his. You can see the cool wind deflector if you look closely. Great custom addition. The car is a wolf in sheeps's clothing if ever there was one. Terry has an eye for quality!
TDR,
I'm like you I like sound, racey sound. I love A-1 headers for the performance, however the mufflers are to quiet for me. In fact I gave away the muffler that I got from them and made my own center outlet with a straight through muffler set up to get a sound like the spider you posted. Now I have a turbo set up that sounds even better with a nearly straight, no muffler, 3 inch diameter, pipe coming off of it.... I can make anything.... I'm in San Diego
Stan's so modest, so I'll provide you with the sound of his car...but you have to promise to close your eyes, use your imagination and just listen. I have only spent one afternoon near this car, but trust me, it's a beast: http://www.youtube.com/watch?v=S1sGzIX_mqo
These are some pics Henry sent me a while back of the setups they do. I like the dual mufflers.
