New Custom Exhaust
 

Well, I decided that I didn't want to spend a lot of money for an exhaust, and since we have all the tools to build one, why not? Ordered the parts from JC Whitney, got them today, and should install in the next few weeks.

Oh yeah, and it was cheap. We'll see how it sounds.

Cat-back, completely legal. :rockon:
3" tips, 12"glass packs, and flanges so it is removable.

Opinions are welcome, but don't bash me too bad.

sound clip?? :D

i just got the parts today, it will take a while to get it installed. haven't even heard it myself yet.

Go for it. Some of the best exhaust systems I have ever done were one's I built myself from parts laying around the house. All my turbo cars have all been home made exhaust systems.

There is absolutly no reason to spend $1500 for a polished stainless exhaust system, thats just stupid. You will never see any of that system under the bumper, the dual 3" tips will look good, and it will probablly be loud as hell, which makes it fun to drive around with.

Tierce, please post sound clips if possible!!!

Glass packs of the late 70’s just got louder the older they got until basically they were straight through!!

But then so is my 2003 S muffler :)

I aprreciate your opinion, I feel the same way. :rockon:

As for sound clips, it will probably be a few weeks until I can get it completely installed. There's a lot to do. And I just realized I'm not sure how I'm going to upload a sound file much less record one. It will have to be something creative.

I'll keep you updated the best I can. The glass packs are 4" cases with a 2.5" center core straight through. So it should rumble pretty good. But the cats will still be there, so it won't be like straight pipes.

You will get your digital camera that does video and audio (most do) and take a video, then upload it to youtube.com for free and share the link, pretty simple..

:corn:

i'll work on it, let you know when it's finished.

I will be curious to see how it all fits in, under there, and sounds. Even more curious if you get DRONE noise and at what RPMs.

I have a 2000 boxster and two years ago I removed the muffler and just installed streight pipes(basicaly a L pipe on each side with tip on each one). It was not obnoxiously loud, because all cats were still on the car, and I basically went through all the local auto parts shops till I found tips that I liked so it was a win win scenariou. Expecially cause it cost me under 50 bucks to build. The sound was awsome, like a v12 when you were at high rpms. Total sound level inside the car when you were running the piss out of it was not bad, not at all, just awsome race car sound. Outside the car, it was distinguishable as to which car was going down the road.(so the girlfriend told me) Also, the car seemed to pull a little harder too. And the tips looked far better than the "common" single oval tip. I was pretty hapby but.....

There was one draw back, horrible DRONE ! Yep, the dreaded DRONE/low resonance was now a major nusance, from about 2500rpm to 3000rpm. (right where you drive in town) From 2200rpm to 2500rpm, it was not as bad. If the top was down, this was not even noticable, but with top up and luging on the freeway, it was very annoying. Please note that I did not have a balance tube.(both exhaust banks were completely separate).

So i decided to try something....
I ordered the Fabspeed cat bypass pipes and I removed the secondary catalytic converters. I now had nothing but the cats that were welded on the headers, all else was completely streight pipes. All 2.5 inch ! Overall sound levels went through the roof, BUT drone noise left the building. After removing the cats, I lost all drone resonance. Not sure why, but thinking it had something to due with the elimination of all that backpressure or just letting the exhaust flow more. Well the sound levels were now very high, and it had a kackle when decelerating. After driving it a good distance on both the highway and back roads I decided to try and isntall the factory muffler again, but leaving the cats off. Doing that made the car almost as quiet as stock but just barely a noticable "rumble" more than a complete stock setup.

My next change, is to kinda do what you are, using race glasspacks but I will be doing a balance pipe to equalize pressuer between the exhaust banks. Or, if I can find turbo mufflers/chamberd race mufflers that will fit under the rear, then I will go that route instead. All I really want to do is take some of the "bite" off of the cat free noise level. Glasspacks will do it but as the other guy stated, they get louder over time.

Best of luck with your projet and I look forward to hearing how your exhaust ultimately turns out. I agree, paying a grand for a couple feet of pipe and a race muffler is a RIP OFF. Build your own and have it chrome dipped or jet hot coated and save the rest of your money for beer!


Tom
Columbus, Ohio

It's going to be loud as hell, and not in a good way. Buy earplugs. :(

I built this exhaust:
http://vorlon.case.edu/~jpv/boxexhaust/DSC_3054.JPG
using a couple of 4" diameter, 16" long Magnaflows. The first problem is that this style of muffler (straight through, perforated glasspack) does not attenuate low frequencies. The second problem is that unless you add about four feet of tubing length your exhaust will drone horribly between 2,000 and 3,000 RPM. When I say horribly, I mean can't hold a conversation, girlfriend gets out of the car and starts walking, break out the Excedrin horribly.

Over 3,500 RPM it wasn't that loud at all, actually it was a bit quiet! The glasspacks do a great job over that RPM. Incidentally, another fellow built a very similar exhaust to this way before I did, and added balance tubes as well. The droning was still there. My next step will be to make the exhaust path longer so I can move the resonance out of the cruising range.

The stock muffler has a back-and-forth design that makes the exhaust path very long - it is very effective in killing the resonance. Porsche has some smart engineers... :)

Edit to add more details. The pipe sizes on mine are all 2" OD. This doesn't mate up well with the stock ~1.8" OD piping from the cats - it's too big. I cut slits in the 2" piping and used a sleeve and clamp to fasten it. It worked well with no leaks. The muffler inlets are 2". It looks to me like yours are 2.5". Your welds won't turn out very nice if there is that much of a gap where the pipes join. Same with at the tailpipes. You'll have to cut everything down a bunch so it will fit. There is not a whole lot of width back there for two long mufflers. It'll be a tight fit near the tailpipes.

Before I bought my 03 PSE, I spoke with the guy that makes the Bursch exhausts (and has since the 356 days). He was going back and forth on making one for the Boxster. I guess at this point, he won't be getting to it. Anyway, he said the problem has to do with the pipes going at each other. It's beyond me, maybe something to do with the vibration/sound waves bouncing against each other. But, with that element in mind, and how narrow those mufflers are, maybe if you can cross the pipes and double back - sort of have the right pipe go over and into the left muffler, and the left pipe go over to the right muffler, then bend back to the center to join (or leave them on the sides for dual side pipes, and cover the center outlet), you may have something. Then again maybe not! But, I'm willing to believe that this guy knows his stuff and the problem is right. It's just whether or not the cure makes any sense!

Jay,

It doesn't have anything to do with the pipes going at one another unfortunately. However, crossing the pipes over and doubling them back would definitely help the problem, because you'd add a bunch of length to the exhaust.

But, see, that's just the problem. The 911s have the same issue, right? They don't have that resonance (that I know of). They even have LESS pipe between the exhaust ports and the muffler. And they have their pipes going towards each other, right? So, what happens in the extra pipe from the Boxster engine to the muffler that changes things?

BIG caveat here. I'm just armchair engineering here. Note all the question marks above. No one should take my comments on this as valid!

Actually, the 911s have just as much or more pipe than the Boxster. Their exhausts cross over to the other side of the car before getting to the (internally long) mufflers.

Well, not on mine. It goes straight from the head to the muffler. Of course mine is 30+ years old. But no resonance.

So, it sounds like my earlier suggestion is more in line with what a newer 911 has. So, why not put in a 911 exhaust?