Punch out the cats

[Young-SC-Owner]

could i punch out the cats in order to free up some flow? or is that abig no no (no emissions) i plan i getting a new exhaust sometime but i dont know if it will be this year jw or am i completly dumb

[darkstar_one]

its called hollowing out the cats and it should work.... but just make sure u punch everything and dont leave pieces hanging cuz u will getr a rattling noise on any lil things that break off...

[68COUGAR]

is that abig no no (no emissions)
Depends on YOUR state laws. Michigan has NO inspection or emissions testing. Some states have a visual inspection ONLY. Some states have an emissions test (tail pipe sniffer) only. Some states do Both the visual & emissions test. California is trying to pass a law to CRUSH ALL CARS over 10 yrs old. So that '32 Deuce Coupe street rod you have siting in your garage, could be confiscated & crushed by the Smog Nazis's!!!

But if your asking if punching out the cats will adversly affect performance, the answer is: NO, it will not hurt performance at all. In fact, it will probably help due to increased flow. You'll still have that 90 degree "through the cat" bend, but at least it'll be freeer than OEM.

68COUGAR

[Scott Long]

The exhaust shop said they could be fined $250,000 for removing my cats, but if the car came in without the cats, they could replace the pipe. They just wouldn't remove them. So I put the car on jackstands and cut the cats off. Drove back up there and said "my car is loud". They fixed it with straight pipe and charged me $50.00 for "custom pipe bending". I got around the rule.

But like Mark said, in MI they don't test yet. So the only way to get a $250.00 personal fine is if you have an anal retentive police officer look under the car if you get stopped. I'm surprised they haven't pulled that crap on me yet since the cops in my town write loud music and loud exhaust tickets. They've never said my SC was too loud though and it can be quiet loud if you get on the gas.

I had the 90 degree bend re-worked at less of an angle.

I would only punch out the cats if your state does a visual inspection. It will flow smoother with a straight pipe in place. If you leave the cat housings the air bounces around inside so the straight pipe flows better. I've seen people cut the cat heat shields off and then weld them over a straight pipe to make it look like a convertor.

[XR7inWI]

It MAY help performance some, but I can tell you from experience on several other cars that hollowed out cats sound absolutely NASTY.

As for performance, I doubt you will notice ANY difference at all because even though you get rid of the restriction from the guts in the cats, you will be creating empty chambers in your exhaust system just after the manifolds that will destroy the exhaust gas velocity. The exhaust gas will enter the empty cat and expand causing it to slow down. Then it must be forced OUT of that empty chamber. It ends up creating some really bad swirling in the empty cats and bringing back most of, if not all, the backpressure you relieved by gutting them in the first place.

I have seen several cars with gutted cats and they sounded terrible when accelerating and even worse on deceleration such as down shifting or coming down a steep hill. The exhaust starts fluttering and popping inside the empty cats pretty bad.

Personally I would either remove them or get some high flow replacements.

[1FASTSC]

Go straight pipes IMO

[Young-SC-Owner]

what do you thin would be cheaper me buying the pipe and bringing it to the exhaust shop or havin them just do it? i was thinking dynomax res or borla but ouch there pricey i mean it would just be a temporary thing for maybe the summer i plan on having it done by july and running it until september or whenever i get some money saved up for exhaust

[Scott Long]

cut them off, put some flex pipe on there, It will barely fit, I blew one of them off on my car, on the way to the exhaust shop, then have them weld in some pipe.

My audi had hollow cats and it would backfire when you downshifted it or let off the gas suddenly it'd pop.

[68COUGAR]

it would just be a temporary thing for maybe the summer i plan on having it done by july and running it until september
Don't waste your money on some tempory fix. Save the temoprary fix money & add to it and get something good.

If it ain't BROKE, don't temp. fix it!!!!!

68COUGAR.

[DamonSlowpokeBaumann]

Just save somemoney and have a shop put new downpipes for you

[Ddubb]

California is trying to pass a law to CRUSH ALL CARS over 10 yrs old. So that '32 Deuce Coupe street rod you have siting in your garage, could be confiscated & crushed by the Smog Nazis's!!!


Where on earth did you get this information ??? Ive never heard of such a thing. And to think that it could actually happen in California, I seriously doubt it.

Do you have any idea what kind of an impact this would have on the economy of the state ?? I mean, it would be crazy almost just to think about what would really happen.

First of all, what purpose would this serve, other than reducing emissions, and help out the auto manufacturers .. most of which are not going to be domestic vehicles.

I'm no economist, but I know that the automotive industry plays a large part in the state economy. Do you know how many Auto stores, Repair shops, Junkyards, Body shops, etc etc .. and other automotive related business that would fail. And out of all of those, the amount of people who would be unemployed. Leaving it up to the state to pick up the tab, an increase in unemployment usually increases the crime rate.
Not to mention the amount of money the DMV makes from vehicle registration. ALot of which goes towards roads, local counties, and public services, like police and highway patrol. So those people are going to be out of jobs. Loss of jobs, Loss of income, Not as many people buying gasoline, thats alot of sales tax and revenue that the state would lose, and in turn, a reduction in alot of other spending areas.

And the mere possibility that somebody would come to my house to re-posess a vehicle, with some form of compensation for my loss ?? WHere does the scrap metal go ?? Straight to Asia. And that wouldnt happen, because im sure alot of people would be moving out of the state, or selling their vehicles to other states.

I dont know, maybe its just me, but I dont see it happening. The politicians would certainly have alot of problems. You do know who the Goveroner of the state is right ??? Cmon man, before you go posting stuff like that, think about what you're saying. Its not as simple as passing a law that would crush a majority of the cars in the state and cause an economic crisis.

Sorry for the hi-jack. But the "smog nazi's" arent that bad here in California.

- Dan

[XR7inWI]

Yeah, quite a few years ago there was a "crusher law" proposed in Cali. but it got shot down for exactly the reasons you just posted. That and the fact that they realised that trying to confiscate and crush people's classic cars, muscle cars, street rods, etc, etc, would likely just result in the one doing the confiscating getting shot. I know if I had a sweet ols hot rod and someone came to haul it away and crush it, they would be leaving in a body bag or at the very least on a stretcher.

The "crusher law" will never happen.... NEVER!

[Young-SC-Owner]

well i thought the main reason the HG's blew was the rectrictive cats ETC? so leave em be?

[Phillio99]

a type of crusher law exsists. Companies can earn credits for crushing cars of certain ages and those credits can go towards the companies own emissions credits where as the more credits you have the less the company has to reduce its own emissions. Sema has an action network with lobbyists in washington to try to reverse this. I never found information saying that restored cars would be crushed.
Phil

[mannysc]

its a true law and the bad crusher law was defeated buit they keep trying to pass it we have all the liberals here in calif as for removing cats i did it its worth a few ponys hollowing them made me crazy they sound like hell

[leeklimala]

http://www.sccoa.com/forums/showthread.php?t=73371

Call Wynn, their worth the money. I LOVE my prototypes.

[MercsSC]

...punching them out ..will let you run race fuels 100 plus octane ....dave

[Young-SC-Owner]

race fuels...lol i can barely afford the unleaded in my truck:p

[thirdbird]

http://www.sccoa.com/forums/showthread.php?t=73371

Call Wynn, their worth the money. I LOVE my prototypes.

Hey leek,

is there any drone at all with those??
What exactly are you running?

paul

[leeklimala]

is there any drone at all with those??
What exactly are you running?
paul

No drone, after the 3" Y it cuts back down to a 2.5" then splits into two 2-chamber flowmasters. The drone is cut out by the downsizing of the pipes (I think) I absolutely love the sound, especially when coasting to a stoplight, nice and rumbly (if that's a word). It also sounds great going under low bridges and overpasses. If I can get my video camera to work I think my dad has the software to convert video to an MPEG and I can post some vid's or at least some sound clips. Maybe this weekend I'll try getting that done.