Hollowed Cats On A 5.3l, Good Or Bad?

[mikystyle]

I got this place that will cut out my cats, hollow them out, then weld them back in for a decent price. Some vehicles need the back pressure and lose power when this is done. Whats would be the case for my 2001 5.3l. I'm looking just to get a little more power and some better sound from my exhaust. Any ideas on the repercussions

[svensk]

You leaving stock muffler intact I hope? You will definitely get more high-end power. I honestly have no idea though about how much it will do to the low end.

 

-never mind I see you have a catback system, you will most likely lose a bit off the line. But wait for other people to respond and get a good census.

[Indy]

If you hollow the cats your engine light will come on. If you want less restriction put on Magnaflow high flow cats. The cats were put on for a reason-POLLUTION.

It's bad enough that our trucks get 15mpg.

[pwall]

And of course if your state starts emission testing, you're gonna have to but new cats back on.

Plus wouldn't the O2 sensors after the cats start to throw a code ? (asuming you have O2 sesnors after the cats).

[hcvone]

As said a high flow cat would be a better choice.

[caddycruiser]

As said a high flow cat would be a better choice.

 

Exactly, and hollowing or trashing existing ones really is just an old wisetale--the difference isn't worth it, and with a decent full exhaust system in the first place, you'll see the most benefit you ever will, and avoid emissions and sensing problems.

 

Just leave them alone, or get high-flows if you really are taken by the idea, and leave it at that.

[mikystyle]

I heard from a buddy that works at a shop that the cats wouldnt affect the emissions test becuase the emissions testing looks at a different type of emissions than what the cats help with. He hollowed out the cat on his jeep that had a catback and after he sold it the guy that bought it got it inspected and went rigfht through NJ inspection without a problem (they do emissions). My biggest issue is cash. High flow cats are a lot more money than just paying some shop to smash out the comb with a stick and do some welds. My main issue is power. I wouldnt want to be losing power due to a lack of backpressure. I had a 89 5.7 in my old truck and i had some flowmaster on it and decided to hollow out the cat on it and made the flowmaster sound great and i couldnt feel a change in power (low or high) at all. I know its kind of a hack thing to do and i know they help with pollution but come on, if we all really cared about pollution that much we wouldnt own these trucks in the first place.

Oh and with the engine code coming up from the O2 sensors, i would jsut have the shop clear that code.

[Loomis462]

you will only see a negative effect of engine performance with gutted cats. These engines were designed to run with cats. in order to run better without cats you would need to put a new camshaft, etc to notice any kind of difference. Dont waste yours or anyone elses time.

[srlbotanical]

Oh and with the engine code coming up from the O2 sensors, i would just have the shop clear that code...

 

 

I don't think your going to notice any difference other than sound. You also can't just clear the code, it will come back because your PCM reads the difference between the pre-cat O2 sensor and the post-cat O2 sensor.

 

If you are hell bent on gutting your cats, the easiest thing to do is install O2 sensor simulators in place of the post-cat O2 sensors. Sims are basically small chips that give the computer a constant simulated O2 sensor reading.

 

Do a search on at summit racing and you should find them...

[YukonDude]

From my experience hollowing your cats will make you wish you would have not done it. The truck i gutted had a set of flowmaster 40 series and i figured would make it louder only to find out it sounded worse no louder just very airy. It made it sound like it was sucking in alot of air. As far as performance it lost power and response. Also, the gas mileage decreased unless you make or by a mil eliminator. But for what its worth save yourself the "headache, time, and money" because you will gain nothing. Just from my experience

[Schmids5.3l]

I wouldnt waste the money, there will be little or no performance gain with this. People with older trucks might, but because they have years worth of soot hanging out. If your looking for simple mods, I'd spend the money on that else were, like some pullies or headers.

[mikystyle]

Thanks guys. Im not doein it. Took your advice and i am putting the money and time elsewhere

[midasman]

hollowing out your cats will throw off your computer cuz your have 02s behind both cats. your gonna kill your gas mileage and lose power

[trxthor4504]

Like everyone has said just leave the cats alone its not worth the time. It will make it a little loader though and you are going to gain a little power, but just buy a good exhaust system and itll be even better. I went with the Borla Cat-back dual side exit, and noticed a huge difference, and if you want even more get a cold air intake, Id reccomend SLP thats waht I have and I love it. Or go with a Volant.

 

Joel