Drilling Exhaust

[RandallNeighbour]

Originally Posted by Wret

There are already some holes just inside the inlets. I assume they were put there to "tune" the exhaust note. If you can enlarge those holes, as mentioned, you bypass some chambers and baffles and allow more sound through.

My buddy and I have tried this. We cut a 1 inch x 2 inch hole just inside the muffler and after two hours work IT DID NOTHING TO IMPROVE SOUND OR MAKE THE MUFFLER LOUDER.

One actually has to tear apart the muffler and remove a lot of metal to get the sound to change, then weld it back.

The bypass system seems to be far more effective. We didn't try that and I haven't heard it on anyone's car as of yet, but everyone who does it says it sounds better.

Personally, I see no reason why you couldn't drill a one inch hole on both sides of the inlets where you would then weld the pipes to the center at a later point. An exhaust leak would sound different as it would be pre-cat near the headers. All the pipes do is route the hot gasses to the center of the car to be sent through the existing tip.

The only issue I see with drilling the holes and not putting bypass pipes in would be heat buildup. Lots of hot gasses building up under the bumper might melt something if you're stuck in traffic. It gets the trunk HOT HOT HOT now, and I'd hate to see what could be worse than what it is with unmodified OEM muffler.

[jmatta]

I highly recommend the bypass pipes on the muffler. I have one installed on my S and it sounds great. It sounds even better now that I've added secondary cat bypass pipes. Everyone wants to know how I get such a wonderful sound out of my car.

[Gubu986]

Does the bypass pipes weld to the inlet pipe entering the muffler?

[jmatta]

Yes, the bypass pipes are welded to the inlets per the picture. You just need to be careful that you don't insert the U-pipe to deep or you'll cover up those holes!

[Gubu986]

Originally Posted by jmatta

Yes, the bypass pipes are welded to the inlets per the picture. You just need to be careful that you don't insert the U-pipe to deep or you'll cover up those holes!

Thanks, Jmatta!

[Christian H]

Originally Posted by jmatta

I highly recommend the bypass pipes on the muffler. I have one installed on my S and it sounds great. It sounds even better now that I've added secondary cat bypass pipes. Everyone wants to know how I get such a wonderful sound out of my car.

Do you know if the diameter of the bypass pipes are critical ?
Yours look to be about an inch or so,would larger/smaller diameter pipes give a different tone or just be louder/quieter?
I have gas and mig welding experience so this looks like quite a straightforward mod unless I'm missing something !

[jmatta]

Car's in storage so measuring is not that easy at the moment. I would think that 1" ID minimum would work, from memory.

Nice that you have the ability to do this yourself...I always rely on friends that are handy.