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I thought I would share this modification that I just performed on these 997.2 cans. Decided to go this route, which essentially is the same as full time PSE, instead of doing the more common gundo hack.
Opened the PSE port by simply grinding the welds on the plug
Ordered this 2 inch SS mandrel bent section from Jegs
I'm just waiting for my shop to pull both cans to do a "Super Gundo Hack" as depicted in the picture below that I copied from another post.
However, in seeing your pictures something seems to be off as far as which are IN and OUT pipes??? Is it possible that the picture below was for a 997.1 and I have a 2009 997.2 C2?
Any help or insight anyone can share would be greatly appreciated since the mods will be done sometime this week. Oh, I'm also installing a set of B&B by-pass pipes.
Astur, I think you need to close off the middle hole. Also, where the escaping exhaust gases converge, you need a Y collector to bring the exhausts together/out.
This combines the bypass pipe effect (not muffling some exhaust) while diverting the rest to the 3rd/unused/PSE outlet.
In the pic you posted, you'd have all sort of confusion as to where the exhaust goes in out.
BELOW IS MY PHOTOSHOP. I never did this hack. I ran two glass pack resonators instead (loud and delicious, but too loud on longer trips. It beat me up. I have a Borla exhaust after hearing one and falling in love. Nevertheless, I suggest the design below, just collect exhaust gases with a more Y shape as they converge going out)
Astur,
The 997.2 cans differ from the 997.1 cans internally and in relationship to flow.
997.2; inlet enters the middle port and exits the bottom port
997.1; inlet enters the bottom port and exits the middle port
Both versions do use the upper port for PSE.
The photo you posted and Philster's diagram are 997.1 cans.
To do a super gundo hack on the 997.2 cans, you would have to open the PSE port and pipe like I did, then add a small bypass pipe between the inlet and outlet pipes.
Wolfk, how does it sound? Best if there is a way to directly compare it to a gundo hack? Side by side comparison perhaps...louder, deeper, raspier? More pse than the gundo?
Astur,
The 997.2 cans differ from the 997.1 cans internally and in relationship to flow.
997.2; inlet enters the middle port and exits the bottom port
To do a super gundo hack on the 997.2 cans, you would have to open the PSE port and pipe like I did, then add a small bypass pipe between the inlet and outlet pipes.
Thank you so much Wolfk!!!
So would it be fair to say that the picture below depicts my extremely poor MS-Paint attempt in trying to visualize the Super Gundo Hack that you suggest?
Well, I drove the car all day today and I am not impressed. The exhaust note is still too subdued for me. Maybe increased the stock note by one or two decibels. Under 3000 rpm there is virtually no change from before. This judgement from my ears sitting in the driver's seat.
I have no first hand audible experience with any other 997 exhaust systems, so nothing to compare to.
Back to the drawing board, will probably try the super gundo hack. Yes, Astur like your depiction.
It looks like you connected the 3rd port to the wrong pipe. The "Hanksville" mod works by connecting the middle pipe (inlet) to the 3rd port. This allows more exhaust to flow into the muffler, which changes the sound characteristics. In your case, you connected the 3rd port to the outlet. I'm sure this also changed the sound characteristics slightly, but probably doesn't impact overall exhaust flow. Check out this thread, which includes an x-ray of the stock muffler.
I'm interested to hear how your exhaust sounds. Could you record a clip of your exhaust? Here's my 997.2 with the standard gundo using a 2" pipe. I went this route as I thought it would be the loudest. It's nice and loud on startup, but quickly becomes quiet. Great for long cruises, but I could use a little more noise!
I am aware of the the Hanksville mod., which only alters the inlet to the mufflers.
I chose the route I took to replicate Porsche"s Sport Exhaust. Where the third port is opened up to the outlet via vacuum operated valves. I did this is assuming sport mufflers have the same internals as the standard mufflers. Maybe they don't, or maybe I am expecting too much. I am looking for something that gives me some audible exhaust note under 3000 rpm. It was just an experiment anyway, more experimenting to follow.
There is the PSE baffle fix link that shows the internals of a 997.1 PSE exhaust. So there might be a difference as the inlet pipe has a cut out to that upper chamber in the photo that allows direct access to the PSE outlet pipe. http://img.photobucket.com/albums/v9...ps4bfe4f57.jpg
Cool, great pic, thanks. Pretty much confirms PSE muffler internals differ from standard mufflers with that internal cut out. Even though that is a 997.1 muffler, I am sure 997.2 PSE muffler would have the same cutout. So actually a gundo hack is essentially the same as PSE. Gundo is an external bypass, PSE is an internal bypass.
This explains why I am not achieving significant results with my modification. Looks like I will now perform a standard Gundo hack.
02-21-2016, 11:09 AM
A different version 997.2 muffler mod
