4-2-1ls header to Skunk2 Mega Power R Exhaust System

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shahzzy

noob
I just bought a greddy header for my LS swap, but will that bolt right up to the civic Skunk2 Mega Power R Exhaust System (for my 1994 civic eg)?

Do I need to make any modifications?
 
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I mean to say, will the following just bolt up?
b18 header 4-2-1 onto the 1994 civic hi flowcat onto the ckunk 2 exhaust?
 
Well, it depends on the outlet of the header you purchased. For example if your 4-2-1 header outlets diameter is 2.25 inches, you need your cat or testube or what ever you plan on using, to have an inlet of 2.25 inches and an outlet of whatever you'd like. Then the cat back exhaust needs to have an inlet size diameter = to the outlet size of the cat.
Correct me if I am wrong.
 
exactly.
but if its a stock sized header and a stock size cat yet it will bolt up.
 
Uh, yeah. They should bolt right up. The size of the tube won't make a difference when bolting them together. It'll only make a difference in the way each component reacts. And the output of the header has a tapered doughnut gasket that will mate with an OEM or aftermarket cat.

Try to keep all the whole exhaust system the same size to eliminate any constrictions to air flow caused by a smaller diameter component. The smallest diameter tubing you have is your focus point for flow. If you have a 2.25" cat and a 1.5" cat-back then you're only running a 1.5" exhaust. Having the larger in/out ports for the cat really isn't doing anything but causing the air flow to back up at the output flange which causes more back pressure. Think of it like a water hose, the smaller the hose the less water goes through. In order to get the same amount of water to go through as the big hose you have to apply more pressure. In an exhaust system, you want to reduce the pressure so the motor does not work as hard to expel the spent gases from the combustion cycle. Make sense?
 
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