okay, i was all excited to install my armor-coat Pacesetter header and cat-back exhaust when half way thru i realize im dorked!!! the end of the header is a cup and ball type fit with compression flanges to secure it. not important! what is important is the opening at the end of my "2.5 inch header" is just a frog hair over 2 inches!!!! issue #2- What is the point of 2.5in exhaust pipe from cat-back when the cat-front is 2-2.25 inches? nice freakin bottle neck! So now, after spending 5 hours just on the header and cat-front install, i have to have the end of the header cut/opened up to 2.5 inches as well as get a new peice of pipe from the end of the header to the front of the cat. I WILL PAY TO HAVE IT DONE FOR ME!!! Exhaust work bites!!!! any input on the exhaust restrictions issue? is that "bottle-neck" needed for back pressure?
thanks for reading the rant...
tim

Maybe they just have that bottle neck because the cat is 2" so they need a 2" pipe connecting to the flange at the cat. The way most people eliminate this is with a test pipe to eliminate the cat completely (1500 dollar fine if caught in CA on streets).

the end of the header is a cup and ball type fit
>with compression flanges to secure it. not important! what
>is important is the opening at the end of my "2.5 inch
>header" is just a frog hair over 2 inches!!!!

There is nothing wrong with a little over 2" opening on the ball/compression fitting. Dont be suprised if you cant seal it after you open the ball opening up. Ball/compression fittings just suck to begin with.

issue #2- What
>is the point of 2.5in exhaust pipe from cat-back when the
>cat-front is 2-2.25 inches? nice freakin bottle neck!

The stock cat inlet/outlet actually bottles down to about 1 7/8" before reaching the actual cat. Whats the point of a larger exhaust despite a small cat? None other than dynos have proven again and again that cat back improvements produce more power even with factory cats. Aftermarket cats rarely provide any additional power without extreme mods like turbo, nitrous ect. I sure as hell didn't feel any power out of using a 2.5" cat or 2.5" piping NA. Had I not had nitrous then turbo I would have switched to something smaller. Greddy's sp exhaust for NA 2Gs is 50mm (2"). They could have used 60mm if it helped. they do on alot of other NA cars.

So
>now, after spending 5 hours just on the header and cat-front
>install, i have to have the end of the header cut/opened up
>to 2.5 inches as well as get a new peice of pipe from the
>end of the header to the front of the cat. I WILL PAY TO
>HAVE IT DONE FOR ME!!! Exhaust work bites!!!!

Never install anything pacesetter at your house unless you have welding, grinding and hella fabrication experience. I had to take about an 1" or mor out of my downpipe to make the 1rst pacesetter design fit (it prodruded at least an 1" past where the downpipe came up to join it). Brospeed went right on without manipulation.

any input on
>the exhaust restrictions issue?

we dont need all these big pipes on out car. it does nothing but kill low end power. The exhuast system is not all that restrictive to our needs. its the same exhaust as the 210hp GST with a different muffler.

is that "bottle-neck" needed
>for back pressure?

no. back pressure isn't needed either. speed/velocity of gas is needed (too big or small a pipe slows velocity). how can backpressure be good, it henders combustion by causing already burned hot gases to go back towards the combustion chamber.

Great info Stan, thank you!
So, if i am going to run nitrous(sitting on floor now )i will benefit from the larger exhaust, right? Even run through the stock cat(appropriatly modified with 2.5 inch flanges, of course)??
thanks

Yeah the 2.5" really helps on the bottle, maybe too much.

The only reason I see for it is to allow the header to bolt up to the stock cat. and why eventually I'm going to get a 2.5" downpipe made with 2.5" high flow cat and 2.5" back piping. The reduction down to 2" is to allow the part to be a bolt on, not weld on part.

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