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This weekend I installed an x-pipe in place of the factory H-pipe, and did a stealth cat delete. I cut open each catalytic converter with my bandsaw, removed the catalyst matrix, welded in a mandrel bent pipe connecting the inlet and outlets, and welded the body of the cat back together. Now anybody can look under my car anytime they want (not that it's terribly easy to do on our cars) and I have nothing to worry about! :eek:wnd:

The car definitely got louder, but most of all I can say that the car is HANDS DOWN faster! Even half throttle acceleration feels like a significant drag has been removed from the car. Pics attached. The first pic shows the materials before welding, the second shows the new dummy cat after welding.
 

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If you notice the inlet and outlet are not in direct flow of each other

When the guts were in it the flow channel was straight.
Gutted now causes the exhaust to ram against the inside of can by outlet and creates not just a sound change but also more back pressure which does not help vacate the cylinders of exhaust.

There is no performance gains doing this ( unless internals of CATS were getting plugged up) but rather the sound change you hear makes it seem like it's faster.

BTW the X-pipe downstream in mid pipe will change sound but cannot help create exhaust pulses to pull exhaust out of cylinders.
Best is replace those phony CATS with X-pipe in that location close to exhaust ports.

BTW any decent smog shop can tell CATs are gutted as the rear 02 sensors will now match the output values of the front 02s and worst case they wack you with a $10,000 smog abuse fine.
It may not effect where you live but if the car is sold to like someone in Ca and the new owner is not aware the CATs are gutted they will have one big surprise on required smog test to get title change.
 

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If you notice the inlet and outlet are not in direct flow of each other

When the guts were in it the flow channel was straight.
Gutted now causes the exhaust to ram against the inside of can by outlet and creates not just a sound change but also more back pressure which does not help vacate the cylinders of exhaust.
With his S pipe he has shown that ram effect would be eliminated. Flow should be as smooth as any pipe with a bend.
 

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Yeah, notice I welded a pipe in there. Gutting a cat is nothing unique (and sounds like crap) and doesn't require cutting to accomplish.
 

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Not only that, but pretty much anyone can smell the difference between a car with a legal cat or not. It doesn't take a visual to know, just 2-3 seconds behind any car will let you know if they have a legal cat or not.

Besides, good lerformance cats don't cut down performance all that much unless you start pushing over 600hp, and one is doing their part in keping the world a little less polluted.

On top of that in most places, fake cats won't get you past the yearly emissions tests.
 

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This weekend I installed an x-pipe in place of the factory H-pipe, and did a stealth cat delete. I cut open each catalytic converter with my bandsaw, removed the catalyst matrix, welded in a mandrel bent pipe connecting the inlet and outlets, and welded the body of the cat back together. Now anybody can look under my car anytime they want (not that it's terribly easy to do on our cars) and I have nothing to worry about! :eek:wnd:

The car definitely got louder, but most of all I can say that the car is HANDS DOWN faster! Even half throttle acceleration feels like a significant drag has been removed from the car. Pics attached. The first pic shows the materials before welding, the second shows the new dummy cat after welding.
Thanks for the write up man. I may get rid of my second cat; I’m in North Carolina where the eagles fly!
 
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