test pipe vs. high-flow cat

Looking on e-bay I found test pipes, but for around $20 more I found high-flow cats. Question is would I pass emissions with a high-flow cat, and would it make a noticable difference in performance? Or would the test pipe be the better option?

I wonder what the manufacture claims about High-flow cat effiecency compared to new OEM. Maybe they would answer an email. There must be a reason that they don't advertise the answer to such an important question. Any used cat has more restriction than when it was new. My guess is that test pipe vs high-flow cat performance isn't noticable and not enough differance to measure. OEM with 100,000 mi vs high-flow at higher RPM may be where the greatest increase in performance is found. I think a good running engine W/ a high-flow cat will usually pass emissions testing in 49 states and won't pass visual inspection in CA.

I had a cat that was bad on a 94 GMC Jimmy I owned. I replaced it with a highflow cat. It gave a little better performance, along with a little bit of a deeper exhaust sound than stock. It also had no problems passing emissions in IL. High flow cats as long as they aren't bad in any way should very well pass emissions in all states except CA. In my case along with several friend cases, the high flow cat actually lowered emissions from what it was OEM.

I just found an old thread where a guy in Utah failed emissions with an OBX high flow cat. What kind of cats were you guys using demotim?

I just found an old thread where a guy in Utah failed emissions with an OBX high flow cat. What kind of cats were you guys using demotim?

I bought a brand new high flow cat from a local performance shop, and it was a Walker brand. I believe that is the same brand my friends used, but I'm not positive. However if a guy in Utah failed emissions using a high-flow cat, the only thing I could think of is either the cat was used and was bad, or that Utah has quite strict laws concerning emissions. The best thing to do, is to contact your local emission testing center, and ask them if a high-flow cat would cause your vehicle to fail. By all means every state has different laws, and even though me and my friends had no problems in Illinois, people in other states may. You could probably check with local exhaust shops also, since most shops will not install something that is against the law, astleast the shops in my area won't.

Would you say another possibility might have been there was something else wrong with the engine? Cars with new OEM cats can fail emissions testing. There are no guaranties that a cat will make the difference between passing or failing. No doubt a new high-flow cat may be more efficient at reducing emissions than plenty of used OEM cats. Regardless of the name on the product many items originate from the same facility. If the cat looks the same on the outside, it probably came from the same facility. Some test pipe pictures look just like high-flow cats. State requirements are not as different as you might think. States that want to measure improved air quality follow what other states have done to measure better air quality and win the federal funding that goes with it. Illinois has very high emissions standards. While it is possible that the right individual at a muffler shop or emissions testing facility may have accurate information... so may a local librarian or fast food employee. Here's some great exhaust flow and muffler info but nothing specificly about cats.
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm

Would you say another possibility might have been there was something else wrong with the engine? Cars with new OEM cats can fail emissions testing. There are no guaranties that a cat will make the difference between passing or failing. Regardless of the name on the product many items originate from the same facility. State laws are not as different as you might think. States that want to measure improved air quality follow what other states have done to measure better air quality and win the federal funding that goes with it. While it is possible that the right individual at a muffler shop or emissions testing facility may have accurate information... so may a local librarian. Here's some great exhaust info but nothing about cats.
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm

JustSayGo is definately correct on that. There are many things that can and does cause vehicles to not pass emissions. I can't say how any other states are on emissions, nor can I say that no high flow cats causes a vehicle to fail. Everything Ive said about passing with high flow cats is based on my own experience, and nothing more.

As far as 48 state or Federal standards and the higher standards required by California, isn't Illinois the other state requiring the higher standards? demotim00 personal experience is very incouraging as far as 4trackmixtape chances of passing emissions in Washinton.

As far as 48 state or Federal standards and the higher standards required by California, isn't Illinois the other state requiring the higher standards? demotim00 personal experience is very incouraging as far as 4trackmixtape chances of passing emissions in Washinton.

I know California cas higher standards, and as far as the other state I'm not sure. I can't say if IL have higher standards than anyone else or not. However it would be my logical guess that if a high flow cat would pass emissions in IL, that it should just as well pass emissions in Washington. However one thing I have always been told and that is it is illegal to replace a cat unless the one on the vehicle is missing or bad. Also if the cat is bad, is it my experience that something usually caused it to go bad, so before replacing the cat, I would highly recommend making sure the vehicle has no other problems and is in good mechanical condition.

California makes it simple. No engine modifacation allowed. If the intake is aftermarket or A/M cat, the vehicle fails visual inspection and exhaust gases (4 rather than 2) are not analyzed. Blue headlight bulbs aren't legal either.

The California Air Restriction(?) Board are really strict about engine mods, but a lot of parts are CARB certified these days. Imagine how much money is made in California alone off aftermarket parts. In 2007 Washington is going to adopt the same standards as the CARB, maybe even tougher.
I'll go ahead and get the new cat instead of the test pipe. Nothing's wrong with the car so I'm sure it'll pass emissions.

Of course 4trackmixtape is right. I know which CA resident told me otherwise. I'm sure CA doesn't loose money researching and issuing Executive Orders for A/M parts. Neither will any other state. Parts will be more expensive as more states get their share. Another slick hidden tax.
http://www.arb.ca.gov/msprog/aftermkt/devices/amquery.php