I'm considering opening up my muffler, enlarging the holes where the pipes enter, thus making what could pretty much be called an internal Pedro mod.

http://986forum.com/forums/uploads02...1467036314.jpg
Drilling by the red arrows would allow the exhausts to follow the blue arrows into the outlet.

Would that work? It would be a fairly easy mod to make, provided you're able to weld or get someone to do it for you. It would also look completely stock from the outside.

Yep, still happy with 3/8" holes. It doesn't change the sound a lot -- it just adds rumble, mainly. It's not going to wake up your neighbors or turn heads when you leave cars & coffee. It's a subtle change, but worth making.

How long does the drill bit need to be?

Check the first post... it shows what tools were used. It doesn't appear to be an extra long bit.

I used 24-inch (60cm) drills. Anything shorter will not reach the spot that needs to be drilled.

https://www.youtube.com/watch?v=PO9l-X4eUOk This guy made a great how / before and after video. He even gives a shout out to Particlewave :cheers:

2ndary cat delete and 2x 1 inch holes. No drone but still too quiet. I might go 2x 1.5 inches or maybe 2 additional holes....

Ha! That's funny :)

I did this mod at the same time that I de-snorkeled and I thought the increased sound was nice, though mild. I'm now convinced that the muffler mod did little or nothing at all, as others have reported on the 2.5, and the increased sound was primarily from the intake.

I can confirm that the 2.5 muffler on my '99 is full of sound deadening material, rendering this mod virtually pointless.
I might crack it open some day to see what can be done.

Or maybe all of the pictures of opened mufflers have just had that material removed before the picture? Can anyone who has opened one confirm or deny?

Edit: I went ahead and enlarged the holes from 1/4" to 3/4" and it did increase low end rumble, though not as dramatically as I'd hoped.

Crios + PSE = ?
 

Wonder what Crios mod is like if you add the Pedro Sport Exhaust mod?

I'm finally happy with sec. cat delete. 2 holes each pipe. 1.5 inch and 1 inch holes on each side. No drone and decently loud. 03 2.7

I'm going to go right through the top of the muffler and into the inlet pipe with one or two 1" holes.

I sold a crios modded muffler to a buddy who sent it to Fister. They do a mod similar to the Pedro exhaust. I don't know if they closed the crios holes back up or not, but it sounds pretty awesome now.

It's a common mod that I've been told works very well. One or two 15mm holes.
You don't have to open the whole exhaust, just open a window on both sides.

Thread needs more pics for us 97 to 99 Boxsters. I need to see where exactly to drill the holes.

i wonder if you could go in via the entrance pipe to drill the holes - similar to the crios mod?

if you do as you say, perhaps a couple of 3/4" knockout plugs to fill the hole - no welding required, do it while the muffler is in the car?

I'm not completely convinced that it does anything on the earlier mufflers because of the sound deadening material inside.

I will definitely look into this. It will be after the 1st of the year before I get to it. If I can't get at it from the inlet, I'll go through the top (don't want the plugged holes to be visible from the bottom).

Any 98ers on here that have made this modification?

Does it work?

better idea
 

Do what everybody else told me I couldn't do cause it wouldn't fit....I installed headers and intermediate pipes from a 06 Cayman and the mufflers already had the secondary cats deleted. My Midas dealer cut and rotated the pipes a little for clearance with no issues. I vinyl ty rapped the wheel sensor wiring to the struts far from the exhaust..wa la! Still there. Sounds great and a steal for a $1000. Sounds way better than Fabspeed. I heard one and thought it sounds the ****************s!

It's "voilà", lol (parlez-vous français?) :D

Only $1000? :confused:
Glad you like it, but that's crazy expensive. You could have had bypass pipes bought and installed for less than $200. ;)

No, you are mis understanding me. I got rid of the 986 headers for 2006 Cayman headers and installed 987 mufflers with sec cat deletes. So I have the less restricted headers and 987 mufflers. So doesn't sound like a heat score through straight pipes!

Why would you pay 200 just for bypass pipes off them crappy 986 manifolds? and still small pipe? With a 74mm TBI and plenum upgrade and the softronics chip, it came together well. And it all looks OEM. Im not the kind of guy to pay somebody like Fxxxxxxd money for just stainless pipe...whats that get you?

Plenty do it and are more than happy.
No, I get it. I just don't get the amount of money some people are willing to spend on some piping. :p

The bypass pipes I mentioned are for the muffler.
I can see how the headers might have cost a bit, but surely there are other, more reasonable options for those with secondary cats...I'm glad I only have one set, so only have to deal with the muffler.
This thread is about modding the stock muffler.

As long as you're happy. :)

Its only money...LOL. Have not seen a Brinks truck follow a hearst to a funeral yet...
And the sound is wicked...nice low toned growl, no drone at any rpm, and 5500 on is wild. Also put on a Chinese made xpipe tip so it looks like a Cayman tip also.;)

No, the Brinks trucks drive to the homes of the descendants. ;) :p

Anyway, back to the topic of modding the stock muffler.

OK :cheers:

Internal muffler bypass that does the same as bypass pipes or the Porsche Sport Exhaust.

1" hole drilled in shell and pilot hole drilled into inlet pipe.


Inlet pipe hole widened to 7/8"


I punched through both the top and bottom of the inlet pipes and widened each to 1", so two 1" holes in each.

The cross sectional area of a 1.5" bypass pipe is 1.77".
The cross sectional area of a 1" hole is 0.79", so I have a total of 1.58" per side...very close to the 1.5" bypass pipe. ;)

I'm going to get the shell holes closed up tomorrow and muffler reinstalled, then I'll test it out on Wednesday, so I'll report back then with results. :)

Excellent! :)

Apologies if this has been answered, but if this allows air to flow more freely and has gains of up to 10bhp, wouldn't the PSE or bypass pipes have the same affect on power?

I've got the bypass pipes on mine and wondered if this had any performance gain.

Ger: performance gain was kind of a joke by Crios. You can increase by allowing the exhaust to flow more freely if combined with a larger intake and throttle body (and may need a tune if airflow is increased by more than 25% because that is the most the ECU can compensate for).

There may be a very slight increase in hp, but it's mostly for the sound. :D

Ah!

Aye I was aware of the throttle body and intake :) it's on my list of things to do, along with the underdrive pulley. Thanks for the confirmation though!

Muffler mod
 

So PW, what's the verdict?

The Universe hates me. :)
It started to snow today before I finished up replacing the o2 sensor, so looks like it may have to wait a few days. I'd hate to start it up without being able to drive it to warm it up.
On the plus side, the local muffler shop only charged me $20 to weld small patches over the holes. I would have done it myself, but even with a good mask, welding gives me terrible migraines.

I would have been ready to go this morning, but had to take the family pet in for surgery. Broken tail...had to be amputated. :(

Holy cow...
 

Really sorry to hear that and hope everything is going to be alright.

Thanks for the concern. :) He is doing much better today.


Now, if only the weather would cooperate. Sure is purdy, though. :D

http://i875.photobucket.com/albums/a...0F46713281.jpg

The internal bypass sounds great! It definitely added low end burble and is louder throughout the RPM range without being obnoxious. No drone.

Here is an iPhone video, but it really doesn't convey much without good headphones or speakers (sounds awful on my phone).
https://www.youtube.com/watch?v=ch0rsKOL5NQ

Update: I've driven the car a few more times and am very pleased with the sound. If I did it again, or opened the muffler back up, I'd probably go just a bit louder with a 3rd 1" hole, but I'm satisfied for now and worry that too much more would be obnoxious.
As is, it's definitely tasteful and sounds more like I feel a Porsche should sound.

Just do it!

Muffler Mod
 

PW,

When you say "opened the muffler back up" did you actually separate the halves? Your photos look like you just drilled through the shell and then through the internal pipes on each end. Also if you did not separate the halves, I assume that you would have to drill another hole in the top to access a second hole in the internal pipes, correct?

I really really like your stab at this modification as there are no external pipes needed for the bypass and therefore it looks much cleaner and is a MUCH more elegant solution.

Neat trick you did there. I wonder if there's a way to get rid of the whine that you hear so prevalently on these early Boxsters as it's winding down from the up rev. In yours, you hear the whine as you rev up too. It's a feature I hear on pretty much every rev video of Boxster exhausts except a muffler delete like the one below, or a GHL muffler. My dansk exhaust exhibits very little of that whine, although I can still detect it a little. It must be the back pressure of the exhaust?

Muffler delete on Boxster:
https://www.youtube.com/watch?v=YbCwcWaJkGI

Sorry, poor wording. :)
Yes, I only drilled a 1" hole in the muffler to gain access to the inlet pipes. If I pulled the muffler off again, I'd probably just drill through the patches I had welded on and remove them the rest of the way with a chisel. Because of their location, I'm sure I could access more of the inlet pipes (rather than drill more holes in the inlets, I'd probably just make the holes that I already made oblong).



I have no idea, though I noticed that it's still there, too. :confused: