Knocking Out Cat Guts

[InterCooL]

i dont get the flames part

my brother bought an r32gtst which got through compliance with no cat anywhere. it never shot flames, backfired, made black soot or smelt bad. but there was absolutely no cat on it

a year later he got a hi flow metal cat. only difference now is that the note is apparently different, -but i cant tell.

Oh and he wont get a $10k fine

[SilverECR33]

how damaging is the fumes to us once we have knocked the guts out..

[mr_rbman]

Just make sure if you do knock it out you put a straight pipe through the cat or it will more than likely lose you power.

I agree with some of the comments and disagree with others, if your making less that 220rwkw's i do believe its pointless and not worth the gains. I have now put a 3" pipe through my cat and to me the Pro's were: a good 10-15kw power gain and boost definitely comes on earlier with less back pressure. The cons are my rear bumper is always black and it definitely made my car louder and dronier!

[noone]

Interested if any one is running a cat with launch control antilag thingo

such as the Bee*R, powerfc pro etc did it blow your cat to pieces?

Have been thinking I would have to go for a decat pipe if I end up running antilag launchcontrol

so curious if anyone else has had any issue's

[sicrb25]

I nocked out the cat centre, running avgas melts sh!t

[MANWHORE]

Thx for the input, you guys love your flames, i didnt know it would blow flames, was just asking in regards to having a bit more power and also coz i dont have and wont have a spare dollar any time soon to buy a cat. Might just leave the one i got as i have a kit fitted and car is getting resprayed next week, dont wanna burn that fresh paint.

This is what I noticed:

1. sound didn't get much louder at all.

2. power increase was a fair bit. For the person who said smashing it will make less power, sure if you get 3" pipe welded through it, it'll have more power, but it's not exactly going to rob power if you smash it out without putting pipe inside. Think of it as a small muffler (cat body) compared to having a plug in your exhaust (cat). It still made quite a difference smashing it.

3. bumper didn't really get any dirtier. Our cars run a bit rich anyways, so the bumper naturally gets a little soot on it. Didn't make anymore soot.

4. smells? not really hey. Exhaust fumes normally stink and of course you shoudlnt' breath them in normally - carbon monoxide. I didn't notice it being more smellier after.

4. flames - come on guys, it's not like it's flaming 24/7 or something. it's not like it flames on idle or something. It flames if you're absoloutely killing it and evyerthing's really hot. If you've been hitting it, and if you let go at wot, then it might flame. The flame is really quick, and it never really burnt anything of mine (doesn't really get near it, just striaght out.

[Forged]

The power difference between no cat and hiflow cat is not that much if you have a decent hiflow cat. and definitely not worth the risk of a $10,000 fine!

I had a 3" cat-bypass pipe made to replace my 3" Metal cat (thats the brand) for testing purpose. It only gained 6rwkw on the dyno and my car was running 250rwkw+ at the time. It would have made even less of a difference for a lesser power car.

Knocking Out Cat Guts? Not worth the effort and risk.

[R34GTFOUR]

bunch of hippies i reckon haha

From my experience i've noticed that:

1. it will make a difference to performance, and if you have a stock 10-15 year old cat in your car that is most likely cloged and melted together then you will gain a nice amount of power.

2. Your car will be slightly louder but nothing crazy, no where near the extent of taking out one muffler.

3. I have seen plenty of cars with no cats what so ever pass the emitions test with flying colours.

For example, my celica had a 3inch hiflow cat, i decided to put in a 3inch decat (looks kinda like a cat but its hollow), notice a very small difference but this would be because i already had a nice flowing cat. Anyway i had to get my plates changed from QLD to WA and i forgot that i had left the decat on it. Passed visual inspections cause the guy was a retard and it also passed the emissions test. This was a car that i hadnt tuned yet and was running the very rich base map tune, and the exhaust consisted of straight pipe and onehks cannon. No dramas...

[Forged]

bunch of hippies i reckon haha

From my experience i've noticed that:

1. it will make a difference to performance, and if you have a stock 10-15 year old cat in your car that is most likely cloged and melted together then you will gain a nice amount of power.

2. Your car will be slightly louder but nothing crazy, no where near the extent of taking out one muffler.

3. I have seen plenty of cars with no cats what so ever pass the emitions test with flying colours.

For example, my celica had a 3inch hiflow cat, i decided to put in a 3inch decat (looks kinda like a cat but its hollow), notice a very small difference but this would be because i already had a nice flowing cat. Anyway i had to get my plates changed from QLD to WA and i forgot that i had left the decat on it. Passed visual inspections cause the guy was a retard and it also passed the emissions test. This was a car that i hadnt tuned yet and was running the very rich base map tune, and the exhaust consisted of straight pipe and onehks cannon. No dramas...

The problem is not every "visual inspector" or policemen that pulls you over would be retard. If the police gets a metal wire into your rear end and find it straight though, you're busted. They wouldn't care if your car passes emissions or not.

[discopotato03]

Anyone who's been around cars a few years can tell straight away if it has a working cat or not - the smell is completely different . As for flames from the exhaust ? shouldn't be doing that with or without a converter - its not there to be a flame or spark trap . If the EFI system is injecting fuel when it shouldn't something is very wrong or the load/airflow sensing device is sending the computer the wrong messages .

Just about everyones got a family and they have to breathe as well .

As for unleaded avaition fuel (Av gas) , this is far from the best fuel to run from purely a performance point of view .

Any responsable person will run a working converter and high flowing ones are a buy bolt affair nowdays .

Every mug that gets busted takes us closer to the day when the RTA will have road side sniffers and the simple cheap light type road side gas analyser . Think about it , you may pass the RBT test/noise test/computer rego check/visual height check etc but if they have a cheap means of sniffing the exhaust (particularly if there's signs of soot and blistered paint) your going to be general revenue's best friend .

The authorities LOVE making examples of people driving performance and import cars . For all of our sakes can you please do the right thing .

Cheers A .

[sicrb25]

I have a hollow cat and the cops are so retarded they tried to tell me i "had no cat". Had to point it out to them.

If you wana do it, farkin do it, you run the risk, we aint yo mamma

Edited May 24, 2007 by sicrb25

[95SKY]

I have a hollow cat and the cops are so retarded they tried to tell me i "had no cat". Had to point it out to them.

If you wana do it, farkin do it, you run the risk, we aint yo mamma

What do you mean hollow cat is that a brand? Even if you have a cat with the guts punched out they will still be able to pick it up by putting a probe in the end of the exhaust then they will probe you with a nice fine. Anyway i had a hollow cat as old mate puts it, and when i changed it to a a proper highflow cat i notcied no difference whats so ever with performance, the exhaust note was just a tad bit quiter. And yes its definatley not worth the trouble and the risks you run.

[Adriano]

"For example, my celica had a 3inch hiflow cat, i decided to put in a 3inch decat (looks kinda like a cat but its hollow), notice a very small difference but this would be because i already had a nice flowing cat. Anyway i had to get my plates changed from QLD to WA and i forgot that i had left the decat on it. Passed visual inspections cause the guy was a retard and it also passed the emissions test. This was a car that i hadnt tuned yet and was running the very rich base map tune, and the exhaust consisted of straight pipe and onehks cannon. No dramas..."

I would be very curious to see what emissions test that passed? There isnt one with a blue slip

[SOOKIE]

I bashed out my cat, slightly deeper note, no noticeable increase in power or response, probably not worth the effort IMO. I don't get any flames, a bit of a smell but thats it. Its worth checking your cat, if it looks screwed, change it or bash it, if it looks okay, then leave it be.

[MZTRBO]

A free 10kws is so tempting...the higer the risk the higher the reward, also great chance to be screwed over..

[BAMR33]

You can always pick a car that has no cat when traveling behind...

Cops aren't totally stupid either, if something smells odd they'll make no hesitation in pulling you over and either defecting you on the spot or sending you in for a machinery.

Best bet get a good quality metallic cat converter

[mickr33]

Keep your old cat for when you need to put it back on for EPA purposes. Go and purchase an old commodore cat, doesn't matter the condition it's in. Go to a workshop and have them weld flanges on to a three inch pipe. Now with the commodore cat you have purchased get them to unpick the outer shell off and weld this over the pipe. Now obviously the side with the small holes in it goes upwards. Now you have a high flow cat. Enjoy

[femno]

You guys seem to be missing the point that these 'hi flow cats' are bloody expensive.

mickr33 has the right idea, and i doubt the cops would carry a 3m long piece of wire around just to stick up your pipe which has 2 90 degree bends in a row

Just pop it out. Everyone knows flames are cool and the earth is dying anyway.

If youre worried about emissions then dont drive a car.

[SiR_RB]

a mate has a white r33 with a decat pipe, and his rear bar gets very black, and now its stained like a yellowish colour

i'ld go hi-flow cat, coz im a tightass and dont wanna fork out $10,000 worth of fines

[made_guy]

i've been considering this myself. :

pros

possible performance/responsiveness gain

possible flames (you know you want em!)

slightly tougher sound

FREE!! - sure we would all like to swap to a nice hi-flow metallic cat, but who wants to pay for one?

cons

possibly more damaging to the environment - although i doubt the people that site this as a reason not to 'punch your cat' are out lobbying to all motorsport leagues to put cats on their race cars, or trading in their high perfomance cars for electrics...

possibility of a fine - heaps of the mods people carry out on this forum are potentially fine-able, though this is definitely not a light issue. in the end its up to you, i'm sure we all occasionally breach the laws (speeding etc) by accident which is also a risk we take. plus now i think they can impound your car (in many parts of QLD anyway) which could make 'swapping to a proper cat for an emissions test' difficult??

like someone said, we aint yo' mumma. and we aint paying your fines so the choice, as always, is yours!