Sorry for my ignorance, I see there are lots of arguments about high-flow cats, and test pipes, and gutting cats, and pros/cons etc. Also some say their test pipes collapse/rattle/break, so what would be so bad about removing the cats and welding straight pipes? I live in florida so I don't have to fake like I have cats (which makes sense for some people that gut their cats). Also PLEASE spare me the "environment" speech, nobody in europe uses cats on their cars and they are more environmentally concious for the most part than us. We have cats in the US because some f**ckers here dont maintain their cars (change oil) and therefore need cats so they dont pollute the air. (Like that a-hole you see running around with that rusted 79' station wagon smoking out the pipe like a mother)

So...I would appreciate any input on my question, forgive me if it sounds like a stupid question, im just curious if anyone has tried this. Thanks

 

Isn't that what a "test pipe" is - a cat replacement?

 

+1
That's all a test pipe is. Straight pipe.

 

What do catalytic converters have to do with dirty or old oil?

Personally I thought that a catalytic converter was an emission-control product that reduces the harmful effects of the exhausts emitted by gasoline-powered vehicle engines. The combustion process creates byproducts. Among these are hydrocarbons, carbon monoxide, and nitrogen oxides. All these gases are, in one way or another, harmful to the environment. It's the function of the catalytic converter to convert these harmful substances into harmless ones before it is released to the environment.

 

thats what I mean...if its just a "pipe", then why do I have to pay $150 plus for one if its gonna do the same as welding a piece of tubing there for $30 bucks? I mean I see so many complaints from test pipe owners, it makes me wonder why they dont just have a muffler shop weld a straight piece through, w/ a hole for the o2 sensor?

 

To paul 350Z: understandable, you know more about the technical aspects of this than me obviously, but im still curious why they are not used in Europe then? Im basing my info on what many high-end european mechanics have told me about the reason we use cats in the states.

 

The test pipes have flanges on the ends to allow you to easily put them on and take them off. Welding would be a lot more trouble, IMO. I've seen that people seem to have troubles with hi-flow cats but I didn't realize that test pipes were a problem too.

I suspect that a shop would charge you a lot more than $30 for a pipe, a bung hole and the labor to do it all. It's not a straight line from the exhaust manifold flange to the Y-pipe flanges so you'd probably need bends in the pipe, that cost extra too.

 

I think he meant to modify his stock cats.. remove the converter, and weld a pipe in it's place.

 

welding in a pipe and bolting on a test pipe is basically the same thing. differances are... the test pipe will be of good quality (nice welds, mandrel bent, etc.) while the pipe your shop welds in will probably have **** welds and be crush bent. you choose which you want to buy/do.