So if I replace the exaust and the headers but dont replace the cat it will be worthless?

 

First... Read this.

...then understand that it's not just larger runners on a header, a header has a scavenging effect to "suck" out spent exhaust gasses so that fresh, oxygen loaded air can be used for combustion (among other things).

 

if thats to confusing...

1)axle back is frome the rear axle back..so like..a pipe and a fart can(worthless unless u worship fast and the furious).

2)a cat back is from the cat converter back...so...the pipes after the cat back to and including the muffler. ( not as worthless,but doesnt do to much without a highflow cat/test pipe)

3) a test pipe is illegal. just to inform you. iv had them on most of my cars.

4)i dont know why you would replace the headers, and cat back, but not ur cat...but if you did. it would not be worthless, but you would still be holdin' back per say.

its really an all or nothin deal, alltho every part helps (some more then others) you wont find alot or perfomance difference, unless u change out your whole airflow system.
(intake, manifold, headers, downpipe/b pipe ( the thing with the rezonators after the headers), highflowcat/test pipe and cat back. changin your valvs and your gaskets on older motors is always good to.

 

Damn thats a lot of ****! Whats a test pipe? I was thinking of purchasing this -

HIGH FLOW CAT:

High Quality T-304 Full Stainless Steel.
Direct Bolt-On, NO Modification Required. Easy to Install.
Increase Air Flow and Performance
DC-S STAINLESS STEEL RACING HEADER:

DC-S 4-2-1 Stainless Steel Header.
O2 Sensor Insertion & Metal Gasket.
EXHAUST:

Light-Weight Design. Made with T-304 Stainless Steel.
Hi-Flow Design. Increase up to 15 HP.

 

you wont see that hp unless you get everything.

 

Whats a test pipe????