Punching out the Cat?

[94_eclipse]

Hey guys, i posted this in the N/T forum but after a couple days no one ansered so.. yeah. I just ordered a stainless header and downpipe. I already have a 2.5 catback, the only thing that will be stock with the exhaust is the cat. Where i live, they do not check emissions. So i was thinking about punching out the cat and just puting a pipe through it (They only check to see that you have a cat, not if its functional). Any sugestions? I dont know if it will sound like crap if i do that or if it would be better off to leave it alone. Thanks

 

[cruisintalonawd]

cut it off take a long screwdriver and start hacking at it then weld it back up

 

[rb25det510]

it won't sound bad if your wondering. i gutted mine with stock exhaust on my galant gsx and it basically sounded no different. for a while i took off the cat and only had just the manifold and the front portion of the original exhaust (basically a downpipe) and it sounded SICK

 

[hedrick]

I gutted my cat on my old 97 eclipse non-turbo and i really didnt notice a performance gain but it did smell like unburned gas behind my car during WOT. As far as sound I didnt notice it becoming louder. Hope this helps.

 

[silver bullit]

Why bother? Unless car is turbo'ed there is no point, youll gain what maybe 3 hp why bother.

 

[cruisintalonawd]

when I did it I notice a little bit of a gain and when I put a 2.25" magnaflow muffler I felt a little bit more but I also think the stock stuff was a little clogged up too

 

[No_Skillz]

Punching out the cat will give you unnoticeable gains. Not to mention the stock cat is pretty expensive. You might be better off buying a "mock" cat off ebay, which is what you're trying to accomplish.

 

[HIGHPSI4]

Yea, won't gain anything. Just leave it and drive.

 

[93_tsi_fwd]

If you have an extra cat, then that shouldn't be a problem and if you dont have to go through smog like CA.

 

[spoonman]

Combined with a full exhaust it will make a difference, not big though. After I took my cat and muffler completely out the exhaust has little detinations inside the exhaust pipe and when it comes out the tail pipe, so you will have tiny little flames come out when you get on it at WOT.

 

[BK85]

Why bother? Unless car is turbo'ed there is no point, youll gain what maybe 3 hp why bother.

True if your a turbo, 3hp added to 215hp isn't much.

But on the NT 420a anything over the stock 140hp is good.

I have a header and a Magnaflow catback on the 420a and have allways felt it is just not complete with that stock cat in there.

BK85

 

[Dsm2nr89]

If you are running a 2.5" just leave the cat on there, it will help with backpressure on your n/t dsm. If you had gone with 2.25" then i would say take out the cat. I had my cat and resonator taken off earlier this week and all im left is with my stock muffler. Car smells funny from behind but the note isnt high at all, just maybe a bit more growly down low.

 

[1stblackawdtsi]

I did multiple dyno pulls on customer cars at the shop I worked at, with a cat and without. All pulls were made back to back, and there was only a consistent 1-3 hp gain with out a cat. Personally that makes it pointless to remove a cat if you ask me unless its plugged up and restricting the exhaust. 1-3 hp is not even enough of a gain to notice.

 

[BK85]

If you are running a 2.5" just leave the cat on there, it will help with backpressure on your n/t dsm. If you had gone with 2.25" then i would say take out the cat. I had my cat and resonator taken off earlier this week and all im left is with my stock muffler. Car smells funny from behind but the note isnt high at all, just maybe a bit more growly down low.

I'm thinking it's 2.25", I'll have to check this weekend.

I think the only way I can get any significant improvement to it is to strap a JATO bottle to the ass end and light it off.

BK85

 

[tommy260]

Cats are worth more then to just "punch it out." If you want to eliminate it do what No_skillz said and buy a mock off ebay and sell or scrap your stock one. Then you can put the money you made from the transaction towards a turbo. ;-)

 

[DSMunknown]

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[No_Skillz]

I led. Thanks for making my morning.

 

[tommy260]

 

[94_eclipse]

If you are running a 2.5" just leave the cat on there, it will help with backpressure on your n/t dsm. If you had gone with 2.25" then i would say take out the cat. I had my cat and resonator taken off earlier this week and all im left is with my stock muffler. Car smells funny from behind but the note isnt high at all, just maybe a bit more growly down low.

I am actually looking for that low growly sound. i love to hear a deep 4 cyl. mine screams above 4 grand, but 1-4 its a lil tinny. Thanks for your input!

 

[94_eclipse]

Cats are worth more then to just "punch it out." If you want to eliminate it do what No_skillz said and buy a mock off ebay and sell or scrap your stock one. Then you can put the money you made from the transaction towards a turbo. ;-)

there is a chance mine is semi-pluged anyway. It has been runing rich since i got it.. O2 sensor problem... Im leaning tward a nock off ebay cat. They are only 30 bucks. But i have a turbo actually, but unfortunatly im a poor college kid and i dont have the money to put into it. Also i need my car to last me 2 more years.. the last thing i need is more problems haha

 

[xveganxcowboyx]

Choking us all to death is totally worth 2 horses. Breathing is over-rated anyway.

 

[BeatupVR4]

Cats are worth more then to just "punch it out." If you want to eliminate it do what No_skillz said and buy a mock off ebay and sell or scrap your stock one. Then you can put the money you made from the transaction towards a turbo. ;-)

Ditto on this. Stock cats usually have a MUCH higher platinum content than aftermarket and fetch a good amount of money. Around $100-150 IIRC

 

[c4uldr0n]

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Don't punch out the cat unless it is clogged, performance gains are not worth it. Replace it with a cat or replace it with a test pipe.

 

[94_eclipse]

Well if i put a pipe inside of the cat and weld it in, wouldnt that be the same thing as a test pipe? I have to have a cat on my car for inspection, but it does not have to be functional.

 

[c4uldr0n]

That would work, just don't make the pipe smaller than what existing and choke your exhaust flow.