Replace Cat with straight pipe

whats up guys, my 95w cat is going bad. it makes an awful sound but still passed emissions:grinyes:. but anyways, instead of replacing it, i wanna do a straight pipe through. is this a bad idea? it would be cheaper and should give a little performance.... right?

Federal EPA violation, 10k fine potential.

ok well thats not gonna stop me. my brother has it on 3 of his mustangs... im just curious to know if it will effect anything like o2 sensors

it will set a code for the rear o2. you would have to put an o2 sim in place of the rear sensor. besides the potential of getting fined, you may have a harder time passing emissions since they still do tailpipe tests on 1995 vehicles.

so i guess what your saying is, its better off to just get an oem replacement?

Mine has a straight pipe. Of course its strictly for offroad use :wink:
I have a 1995 also. No check engine light at all. The big difference is the sound of the exhaust, it really opened up. Not loud at all, cause the muffler is just a muffler man special. But I have had several people ask what kind of exhaust I have.

Ill tell ya right now what most people are going to say:
1. There wont be any performance difference.
2. If your cat is bad its cause of something else. Fix that and replace the cat with some $400 one.
3. Youve already herd "Its illegal".
4. Youll have a check engine light on all the time.
5. Im telling the cops. J/K

Heres what I say. If your getting tailpipe tested, you gotta have one, cause otherwise you'll fail.
If not do your thing. Yes its illegal. So is speeding, and so is being drunk in public but that never stopped anyone.
AFAIK 95's are OBD1.5 and you wont get a check engine light cause the after cat sensor is not used. If you do get the light, do a Search (www.dogpile.com) on the internet. For like $30 you can get the bypass thingy.

And as far as performance, I cant say anything about 1/4 mile or HP. Cause, c'mon its a blazer. But what I can say is, after I took mine off I gained like 2 mpg overall. And when I punch it, it just plain feels good ;)

PS is your avatar beetle juice?

thanks alot. that helps.. and the thing is, i live in philadelphia... capital of the $25 inspection sticker. you people think im stupid? ahh.. anyways im just affraid of sensors goin off... but i havent seen any after the cat anyways..

On a 95 ya you wont get a check engine light cause its pre OBD-II there is no downstream O2 sensor. As far as performance i dont think you would gain anything because the engine is computer controlled and affecting backpressure is not going to change anything. However I could be wrong im not sure about the 95's all i know is that my 2000 s-10 4.3 4x4 with a magnaflow high flow converter and custom dual exhuaust didnt yield 1 hp or .1 mpg! Sounds cool though! I have done countless dual exhuast jobs on computer controlled trucks and the customers always dissapointed that they just spent 500$$ for a cool sounding truck! However if your cat is bad then who cares put the bypass pipe on it just dont get caught!! I do know too that if a shop cuts out your cat its a 25k fine for them! OUCH! Do it if your sure you wont get caught but its only 60-120$$$ for a universal but its about 350-550 in a shop.

On a 95 ya you wont get a check engine light cause its pre OBD-II there is no downstream O2 sensor.

And where did you derive this statement?

I own a 1995 and yes, there is a rear O2 sensor and yes, it is OBDII which in most cases, 60-80% of 1995 blazers are.

If you don't know for sure, don't post.

thanks alot. that helps.. and the thing is, i live in philadelphia... capital of the $25 inspection sticker. you people think im stupid? ahh.. anyways im just affraid of sensors goin off... but i havent seen any after the cat anyways..


Replace the cat with a high flow catco 2.25" cat off of ebay.

Cheap , flow really well and will have you still being legal.

Removing your cat is just a stupid thing to do. You will have to go in to have it inspected so why not have it fixed properly so you don't have to pay a fine on top of installing a new cat as well.

Common sense, I think you should remember that you are breaking the law and you will only lose from doing this.

auto zone sells the perfect size 3 inch pipes to replace a cat with. Only like 10 bucks for everything you need.

auto zone sells the perfect size 3 inch pipes to replace a cat with. Only like 10 bucks for everything you need.

And completely illegal.

And completely illegal.never said i was driving it on the road like that.

never said i was driving it on the road like that.

True, but this thread isn't about off road Blazer use.

removing the converter is a federal offense so if you do it and get caught, your screwed.

If they do a visual inspect while "sniffing" like they do here, they'll be looking for a catalytic converter with their little mirror on the end of a stick. No cat-no pass.

If they do a visual inspect while "sniffing" like they do here, they'll be looking for a catalytic converter with their little mirror on the end of a stick. No cat-no pass.

Actually, no cat, and they will fine you up to $10,000 if they see it as being a recent removal.

easy way around it is to hollow out the cat so it will pass visual inspection. might fail emissions cause of excessive flow or the rear O2 tripping the check engine light. if the factory cat is bad, just replace with a high flow one to maintain legality.

For sure, the difference in flow between a high flow and a hollowed out cat is slim to none.

I read in an import magizne where they tested stock cat, high flow cat and no cat. this was all tested on a stock civic, and the high flow cat gave the same horsepower as the test w/o a cat, and it was legal. For the most part i think its clear that a highflow cat is worth the money compared to risking a big fine. But its your wallet

You are right. Little difference.

I still chose no cat . You can always just take it off after inspection. I never heard off a cop pulling you over cause you dont have a cat.

Actually, no cat, and they will fine you up to $10,000 if they see it as being a recent removal.
do you have a source for that?

My friend was pulled over 2 days ago for a speeding ticket, and during the process the cop looked under the car to find no cats on his mustang, he was fined $450 per missing cat (4 are stock on a mustang) and was directed to the smog ref station.

Expensive ticket yes, but not $10,000.

and this was California.

also, FWIW, local police/state cops are not trained smog tech's, so the ticket can be fought unless it was a highway patrol that pulled you over.


I run 364 days a year with no cats on my mustang and have never had a problem with cops, that 1 day a year when I have 4 cats on the car to drive it to the smog shop and back home is horrible, the car loses a TON of power.

Thats unheard of were i live in Pa . I had a trans am for years and was pulled over a few times for speeding with headers, no cats and loud mouth exhaust, but they never checked a thing on my car . Sucks for your buddy. I guess Cali's got strick rules on that stuff . im going catless still.

Check your local emissions laws. Thee is a maximum fine they can impose. And in most states that fine is hefty.

But anyone running around with cats are just careless individials that like to poision the environment for no benefit.

A high flow cat doesn't restrict exhaust flow at all.

One fine and there goes the cost of having them installed.

Pointless and just a selfish action.

Check your local emissions laws. Thee is a maximum fine they can impose. And in most states that fine is hefty.

But anyone running around with cats are just careless individials that like to poision the environment for no benefit.

A high flow cat doesn't restrict exhaust flow at all.

One fine and there goes the cost of having them installed.

Pointless and just a selfish action. it is just as illegal in california to have high flow cats installed onto a car, as running with no cats.

no CARB#? Not legal. There is no catted mid-pipe sold for mustangs that has a CARB# fyi.

Technically in California its illegal to do anything to your exhaust.

only to the cats, anything after the midpipe is perfectly legal.

it is just as illegal in california to have high flow cats installed onto a car, as running with no cats.

no CARB#? Not legal. There is no catted mid-pipe sold for mustangs that has a CARB# fyi.

We are not talking about California, anyone removing their cats will be fined. And if the inspection guy gets anal or has a bad day, he can fine you $1000s for it in a state that has emmissions laws.

Besides, cats don't reduce horsepower anyways.

We are not talking about California, anyone removing their cats will be fined. And if the inspection guy gets anal or has a bad day, he can fine you $1000s for it in a state that has emmissions laws.

Besides, cats don't reduce horsepower anyways. where's your proof that cats do not reduce horsepower?

my car makes 2psi LESS BOOST when I have the stock 4-cat H-pipe on for emissions.

that's 20-30hp!

Is this the Mustang forum? No....

We are talking about a Blazer here, not your Mustang.

There is no difference in power or economy on a BLAZER when you have a cat vs no cat.

where's your proof that cats do not reduce horsepower?

my car makes 2psi LESS BOOST when I have the stock 4-cat H-pipe on for emissions.

that's 20-30hp!

I'm surprised that you don't see more of a loss than that. Stock cats do restrict the exhaust, having four of them should definitely hurt performance. The high flow cats that BlazerLT is talking about have a flow comparable to no cat at all. A Blazer only has one cat, so any performance difference between a high flow cat and no cat on a Blazer is negligible, and probably not noticeable.

Also if you have no restriction you will lose all your low end torque.