Anyone modified an old CAT
 

1) Can you disable an old CAT without any negative impact?

2) Is there any significant noise impact when replacing CAT with by-pass pipes?

Thanks,
Dan

Here's a guy who just put a cat bypass in:

http://forums.pelicanparts.com/porsche-911-technical-forum/406829-i-lost-21-pounds-but-my-neighbors-gonna-pissed.html

I just did that. The difference in weight (Bursch bypass) is about 7lbs. I did notice a bit more torque around 3500rpm with the bypass and stock muffler. Sound was basically the same. Check the thread from the previous post for feedback with a cat/muffler bypass setup that I will be finishing tomorrow. Looking for my earplugs now.
You could have the old cat punched out too. Basically the same as the bypass without the weight loss I would think.

Really? Taking off a Cat typically reduces torque because you lose "good" backpressure.

I think with the stock heat exchangers, which are supposed to be the more restrictive part of the exhaust system there is back pressure. Again, I am no expert.

If your old cat is plugged, you can empty it out. The interior is three ceramic "bricks". All you need is a steel rod, a hammer, a vacuum, and time.

If your cat is good, you'd be better served to buy a bypass pipe and save your converter for reinstallation later.