Hollowed out catalysts - Power or No Power?
 

Do Hollowed-Out Catalysts Make Power? - Fact Or Fiction
Debunking Tuning Myths
By Luke Munnell

When searching for urban-legend power adders to test for Fact or Fiction, we need only to think back to a time when we were first starting out as broke-ass noobs, conniving ways to make our Civics go faster for the low monetary investment of $0. One of the first such methods we've all tried was to gut our cars' factory catalytic converter, to reduce exhaust back pressure, and ideally, free-up a few ponies by doing so.

Today, with ready access to test cars, OEM catalytic converters, floor jack handles, test pipes and dynamometers, we're revisiting our MacGyver power-making tactics of yesterday, to see if running that hollowed-out cat at the drags really did help us reach the traps quicker. For kicks, we'll also put it up against an OEM-spec catalyst, and a properly built test pipe, to see which comes out on top.

http://i118.photobucket.com/albums/o...Bai23/Run1.jpghttp://i118.photobucket.com/albums/o...Bai23/Run2.jpghttp://i118.photobucket.com/albums/o...Bai23/Run3.jpg

The Verdict:
Compared to our baseline runs, we were able to see no benefit of the hollowed-out cat versus leaving its catalyst core intact, and compared to the test pipe, there was no question; the gutted cat lost all around. Exhaust gasses became turbulent as they passed into the cat's open reservoir, actually increasing backpressure and hurting power. As we had suspected, replacing our car's cat with the test pipe cost a few low- and mid-range ponies and lbs-ft (bad for daily driving), but more than made up for it up top (good for race day). Bottom line: Keep the cat intact for the street, replace with a proper test pipe for the track.


Enjoy!

not to metion it stinks like ---- running it hallow

grt a high flow the add horses and still pass emisions

I agree with the hi-flow cat. Companies like Randomtech, Magnaflow, or even Vibrant makes pretty good hi-flow ones. I would recommend Randomtech though. Think about all that crap you're putting into the atmosphere.

a punch cat sounds like ----, it's all tingy sounding, and the cops can tell very easy from the sound. Just get a Hi-Flo cat.

i did something like this back in the days on a 4cyl domestic car, it ran terribly sounded even worse lol. you lose out on back pressure which you need to gain some hp... sure its free flow but you actually loose at the end... thats from my experience!

i think a turbo application might benefit (back pressure). but it really is not that great.

On a N/A keep your cat, on a boosted car use a test pipe.

Gutted cats sound really bad too

I cant remember exactly who makes it but theres a company that makes a testpipe with mounting tabs to bolt on your cat housing...best of both worlds

On a NA street car go high flow cat.