bottlenose

thats right dont get one it will break down the piping for your headers. Because of the major decrease in back pressure the hot air gets trapped in the headers for a longer time and the headers may even begin to glow. it causes premature rusting. dont get one , oh and same thing with header wrap dont get that stuff either.

Shingoblade-GSR

How does a decrease in back pressure cause the air to become trapped in the header for a longer time????

You are correct about the header wrap though...

Shingo

bottlenose

the cat acts as a collector for emissions and also collects a great deal of the heat that is diffused from the header. backpressure is what keeps the exhaust flowing smooth and keeps gas milage at an optimum. When u dont have back pressure you get back-firing and worse gas milage. the decrease in back pressure results in the hot air staying up by the headers for a longer time...not like seconds but more like nanoseconds basically enough to cause the headers to get hotter faster.

DB7 2.0

i dont think you understand the principles of "backpressure"

but anyway... if the cat "collects a great deal of the head that is diffused from the header" as you say, what does that matter if the cat is already after the header? :eh:

pomansouth

i wont believe it till i see proof of it. sry something just tells m that when it is easier for the exhaust to flow that the heat will not stay by the headers for a longer period of time but it would be vice versa or so it seems. just show some proof please and then i might be satisfied about your statement.

integra_blurred

OK, I think I understand the point he's trying to get across, but he's not entirely correct. It's not so much test pipes that are bad, but if you have a high flow cat or test pipe that is too big the exhaust gases loose their velocity. First off, you have to understand the process of building an effective exhaust system, and realize the "honda's need backpressure" theory is a myth. I'll post more later, got to go.

mrhonda_187

I believe the only 'con' against test pipes is that they stink, and are bad for the environment. Your 'theory' is groundless without supporting data. I'm inclined to call bullsh!t on this one, as I don't think you have a clue what you are talking about.

integra_blurred

OK, I had to change classes, finishig my post...now, if you understand why "hondas need backpressure" is a myth, then you'll understand why what he's saying is wrong. See, imagine and ordinary garden hose. now when it's on the water slowly falls out of the hose, but when you put u're thumb over it the water shoots out quicker. Now, in this instance, the hose is your header, and your thumb is the cat. Now, you want to find a cat or test pipe that will flow the maximum amount of exhaust gases possible, but at the same time, still be small enuf to have good exhaust gas velocity. Now if you have a test pipe that's too big, the exhaust gas will have no velocity thus staying in the header longer, proving his thory, but on the other side, if your test pipe isn't too big and is correctly sized, the exhaust gases will still have good velocity and will flow out of the header as quick or quicker then stock, proving his theory wrong. Rather or not is theory is right depends on the size of the test pipe in question. That's your answer, hoped this helped, gotta start doing work now. for more info pm me. laterz!

teg_fan

Wouldn't the velocity of the exhaust stay the same in the header?? Because you are not changing you header to a bigger one, wouldn't the velocity of the exhaust just slow down when it gets into the bigger test pipe. I don't see how exhaust could possibly stay in the header, if it stayed there would be no room for the upcoming exhaust to come in and would creat back pressure. I don't know too much, but this whole thing doesn't make sense to me at all, logically that is. Please correct me if I'm wrong so I can understand this. :thumbup:

bottlenose

each header / each individual pipe doesnt have exhaust flowing thru it constantly it has short rests between, a substantial decrease in backpressure leaves that heated gas in the pipe for a little longer thus causing damage to the header. Yea as integra blurred stated i am talkin about a larger test pipe then you should have. high flow cat that is matched to your exhaust system in width is probably alot better.