oem muffler hack - 986 Forum - The Community for Porsche Boxster & Cayman Owners

j.fro · 10-10-2007, 01:48 AM

See where the arrow from #3 is pointing? That's where you want to cut. You don't have to cut the muffler open; you don't even need to remove it from the car. Pull the rear bumper cover, then disconnect the pipes going from the cats to the muffler. Using a cutting wheel on a Dremmel extension, an air chisel, or whatever you can manage to fit into the muffler intake pipe, cut holes in the pipe. Do this on both sides. The more you open it up, the louder it will be.

meerzee · 10-10-2007, 03:29 AM

I am confused...drilling and cutting mufflers for better sound? No offense, isn't this getting a little ricey? Last time I checked this is a Porsche Boxster, not a Chevy Cavalier. If you are going to replace the exhaust then fine, but let's try to draw the line somewhere.

Peer · 10-10-2007, 04:35 AM

The more I look at this picture, the more confused I get. What do the numbered arrows represent, and is this muffler pre-mod or post mod...?

-- peer

Kirk · 10-10-2007, 08:52 AM

Quote:

Originally Posted by Peer

The more I look at this picture, the more confused I get. What do the numbered arrows represent, and is this muffler pre-mod or post mod...?

-- peer

Based on another stock muffler cut-away photo that I have I would say this looks like an unmodified muffler. The arrows show the flow of exhaust gas through the system.

Kirk · 10-10-2007, 08:54 AM

I think that Tool Pants originally posted this cut away photo of a muffler. Again, I believe this is stock.

Cloudsurfer · 10-10-2007, 11:09 AM

As I am getting more and more annoyed by the drone of my FabSpeed system, I am looking into alternatives. I'm honestly almost at the point of just putting a stock 03-04 S muffler back on the car with secondary cat bypass pipes.

Cutting these holes into area "3" is not going to enhance flow, its only letting more sound come out (unless I am mistaken).

Patrick

Peer · 10-10-2007, 11:15 AM

Kirk wrote:
> The arrows show the flow of exhaust gas through the system.

Okay -- so I can follow the three first arrows, but arrow #4 makes no sense to me.

-- peer

10-10-2007, 01:27 PM

My main objective is more flow, and no drone. That discounts just about all aftermarket exhausts. As for flow, I suspect that is how the factory hobbled the 986s. My assumption is based on 996's and cayman's have more output/liter and basically the same motor. What is different is the exhaust plumbing.

987 has a revised smoother header (more hp too for that model).
Both 996 and Cayman use seperate mufflers for each bank, instead of the all in one 986. I think this builds a case for restrictive OEM 986 muffler. Each muffler does not fight the other.

Looking into 986S inlets, the pipe goes straight through! Each bank is fighting the other, then spills out in the middle, and onto the other chambers. The first pic I posted is misleading in that way, as the inlets look skewed. They are not. They go all the way through to other end.
Judging from the pics, I'm still not exactly sure how the exhuast is routing. Does the outlet pipes extend to the last chamber? I cannot tell on the right side.

I may have to cut open mine for a better idea. Does anyone have more pics the'd like to share?

j.fro · 10-10-2007, 03:05 PM

The muffler has 5 chambers: Two outer, two intermediate, and one in the middle. The inlet pipe does go straight through the muffler. The incoming gases cause pressure, forcing themselves through the perforations into the intermediate chambers. I believe this action reduces much of the resonance in the exhaust. After the gases are in the intermediate chambers, they are forced into the outer chambers. From there they are piped to the center chamber, then out of the muffler. The Porsche Sport Exhaust uses external pipes to carry exhaust from the intermediate chambers to the exhaust outlets. By cutting into the intake pipe and allowing gases to flow directly into the outer chambers, you are creating an internal "Sport Exhaust". Modifying the exhaust in this way probably won't give you more flow, but it does produce a great sound, with only a bit of resonance.

If you want greater flow, the issue is first the header design, and then the bottleneck of the exhaust piping. The exhaust piping tapers down to 1.75" OD just after the headers.

CJ_Boxster · 10-10-2007, 04:03 PM

Quote:

Originally Posted by Peer

Kirk wrote:
> The arrows show the flow of exhaust gas through the system.

Okay -- so I can follow the three first arrows, but arrow #4 makes no sense to me.

-- peer

in #4 you cant see it but there is another pipe that leads out to the exhaust Tip, You can see it better in Tool pants picture.

Peer · 10-11-2007, 03:25 AM

Well, I'm still confused -- can't figure out how that stock muffler really works internally. Besides, comparing the pictures, there's obviously some difference between the 986 and the 986s muffler (assuming they both are stock).

The reason why I'm eager to know how a stock 986 muffler works, is that I recently bought one to try do a hack myself... but before cutting it open, I thought that I at least needed to know how it works -- but so far no luck.

I might need to emphasize that I'm looking for performance enhancements rather than sound, although I wouldn't mind if also the sound was improved (as long as it's not too loud or sound buzzy).

-- peer

Gubu986 · 10-12-2007, 12:11 PM

Arrow #4 is indicating the final exit.

Wret · 10-19-2007, 05:24 AM

The outlet pipes are plumbed to the two outer chambers. Enlarging the holes in the inlet pipes at that point would allow more direct flow from the inlet pipes to the outlet pipes. I believe some people do this without cutting the muffler apart by grinding away with a dremel attachment down the bore of the inlet.