I purchased a used stock 997 exhaust that I am going to modify. I was thinking of just connecting the inlet and the outlet pipes using a small diameter pipe, thus increasing the sound level a bit. Anyone have any other ideas as to how I could approach this project? Perhaps modifying the internals instead?

 

check out 996 board for a PSE mod thread will give you the basics with plenty of pics

 

tripleinboard, this sounds like the best way to get more noise from your exhaust.
i initially tried the "996 mod" but dont hear much of an improvement.
connecting the inlet and outlet should get you close to bypass pipe sound but not as annoying.
i am gonna try this too, let me know if you get it done before me. my car is still in the body shop

 

Someone (I don't recall who) did a different mod to some stock 997 mufflers about 2 years ago. Here is a pic of the modded muffler. He did not post a video.sound clip so I can't comment on the sound. FYI.

 

hey gota911, that is the same mod i did. that looks like the 996 mod (isnt it?).
anyway i felt this mod didnt do much on the 997 and am gonna try the other way to bypass between inlet/outlet

 

Raffi - Yes, that mod to the 997 mufflers (1st pic) looks a lot like the MKII mod (2nd pic) for the 996 "cans."

I believe you are thinking about doing something similar to the 996 Mk I mod (3rd pic) which should give you some extra growl since some of the exhaust coming from the cats completely by-passes the muffler and goes directly to the outlet pipe and then out the tips. BTW - I think the Mk I mod uses a 1.0" to 1.25" connecting pipe.

 

yeah Tim, the mk1 mod is exactly what i am trying to do.
now i gotta figure out if there are gonna be any downsides to having both the mk1 and mk2 mods on the same mufflers.

 

I have modified the insides of my 997 mufflers but not installed them yet. They were cut open and both the inlet and exhaust pipe was cut.I am unable to post photos. Anyone wanting photos or info are welcome to email me at

 

I just figured out how to post a photo........... the area in blue was cut away.

 

thanks sirpzalot, you have to let us know how it sounds.
i am gonna do the other mod within a few weeks, so please keep us posted.
i will ask my muffler shop which mod will be easier, your idea would definitely be a cleaner modification.

 

Do you have any photos of the internals before the modifications?

 

that is the before...
he removed the sections of the pipe that are covered with blue tape.

he essentially made a connection between the inlet and outlet pipes in that first chamber.
the other way is to connect the inlet/outlet from the outside like in gota911's pic 3 which shows the "mk1 mod"

 

I decided there was not enough sound available when doing the exterior mod. Over the years I have built or modified many exhaust and was very puzzled by the insides of the 997 mufflers. After a lot of thought I decided to go for maximum noise,which there may not be much of. Since others are using a by-pass pipe (no mufflers) then the cats. must be reducing a lot of the noise. I figure by utilizing some of the original baffling it should be quieter than the by pass pipes and hopefully a more sophisticated sound.
Once installed I will let you all know how it sounds and if there is anyone in the San Diego area that can help me post a video..........

 

do you think you will lose any noticeable torque with this mod? also do you think i can do this internal mod that you have done in combination with the external mk2 mod which i have already done?
thanks

 

Raffi, I really doubt there will be any loss of torque.You can do this mod in combination with what you have already done but the noise might be even louder than my setup. Consider selling your mufflers to someone that is not after as much sound.Take their mufflers on trade and
I could modify your mufflers or anyone else's for $320