911Steve

Can a Gundo hack "Muffler Bypass" be reversed? if I get the Gundo hack and later down the line I want to put back to stock can this be done?
Thanks in advance,
Steve

Spokane5150

Sure but it will look like a bloody mess. They have to chop off the bypass pipe and saddle weld some plugs in the holes. Trust me....you will not want to reverse the hack.

Rocco07

Or I'm sure someone would trade you stock for them.
You might even make some money.

911Steve

thanks for the advice....and encouragement!

larrytrk

There are always a set of used original mufflers floating around, generally cheap!

82_930

I have been toying the idea with the Gundo hack myself (this is the hack that simulates the PSE unless I am mistaken)...
Question: Does the Gundo hack drone at all?

Spokane5150

No droning brother. You'll love it. If you have 997.2 you'll want to bypass the rear muffler as well.

You're right about the PSE. There is the same type bypass pipe with a vacuum actuated valve. Push the PSE button and the valve opens allowing the bypass. Fister uses a 1.75" bypass pipe which may be bigger than the PSE bypass. Take a look at this link for more information: https://rennlist.com/forums/997-foru...undo-hack.html

"Wack without the Hack"

Andrew Ward

I just had the hack done yesterday.......what does it mean when you say by pass the rear muffler as well?.......thanks.

PHX 911

2 different animals depending on cars.

997.1's - do the hack for better (louder) sound - these cars only have the two side cans.
997.2's - replace the center silencer with the X pipe - I'm not aware of anyone hacking the side cans, too, but you could. Usually, getting rid of the center silencer satisfies most folks. These cars have 3 mufflers - the center silencer, and the side cans.

Andrew Ward

Ok I have a 997.2 thanks

PTParks

Check your data. The side cans are the mufflers that are modified with the Gundo Hack. I don't recommend the x pipe. The x pipe has a tendency to sound good but it kills low end torque (according to either Sharkwerks or AWE, can't remember which) while the crossover pipes provide a slightly different sound but do not affect low end torque. The stock center muffler has two sharp internal bends in the flow path. The crossover pipes eliminate this and provide a straighter pathway for the exhaust to travel.

I installed the crossover pipes first and did not hear much difference in the sound. When I added the Gundo Hack the sound really woke up. I get compliments all the time on how good the car sounds. There is absolutely no interior drone at any RPM.

cv997

I have a video I made comparing the before and after of a Fister mod on a 997.2. PM me if you would like to hear it.

PHX 911

Crossover pipe, X pipe, same thing. You're the first I've heard that got rid of the center silencer AND did the Gundo Hack on a 997.2. That must be loud as ****, although I wouldn't know, as I replaced the entire system.
Here is a pic of my Tubi exhaust, where you can see the crossover/x-pipes that eliminates the center silencer on 997.2's. You can also see the side cans that were also replaced with the Tubi cans.

Andrew Ward

I was told that doing both the Gundo hack and the center muffler impacts low end torque......is this correct?

slicky rick

Hey andrew, what is your initial impression after doing the gundo? Honestly how did youu. Feel after hearing the mod the first time you started and ran your car?