what you'll want will be like this..

header
flex pipe
first o2 sensor
hi-flow cat
second o2 sensor
glasspack (optional)
rest of piping
muffler

when you buy headers, you get a flex pipe, and a straight pipe (also called "race cat" and "test pipe") included. the flex pipe must be right after the header, and u definitely need it. right after this is where u would put the "race cat", but instead [of the race cat] you will buy/install a catalytic converter. one o2 sensor must be before the cat, and one after the cat. the cat is essential to keeping the car legal, the air clean, passing emissions, and keeping the check engine light off. then to keep it quiet and sounding good (this is optional, you don't need it), you'll want a glasspack. they're cheap and will keep the noise down. then you just have the rest of the piping and a muffler. for the muffler i suggest a nice magnaflow.

 

How you plan your setup really depends on if you have one cat or two.

If you have one cat (the one on the manifold) and one cat only, you'll have to buy another and have it welded into your system.

If you have two cats (like US spec Tibs) then you can buy a header, which will include the actual header and the flexpipe. That will end at your second cat and eliminate your first one. Then you would run 2.5inch piping from the other side of that cat to the back of your car. You'd then extend the second o2 sensor past that cat so you wouldn't have any CELs.

 

no ham...because you're not gonna keep your 1.75" stock, restrictive cat when you just upgraded your whole exhaust system...
you need to buy a 2.5" hi-flow cat fing02.gif

 

wait till you get the headers, flexpipe and the high flow cat installed then get the exhaust done from there, that way, you'll have a 100% fitment for everything...

but make sure that the exhaust is somehow bacwards compatible to the stock in case you decide to go back, sell, upgrade, etc

 

ok. i checked things out and i have only 1 cat converter (high flow) and a magnaflow muffler. i was thinking of getting obx headers, keeping my stock flex pipe, and adding my 2.5 exhaust right after my flex pipe, and putting on a 2.5 cat converter. would this be a good setup?

 

One hi flow cat is all you need. I couldnt really understand if you wanted to go get another, but one is fine. The cat should be put close to the header. You could use a long glasspack and no muffler is what I would do if I had a custom exhaust I would choose to have it replace the cat under the car with hi flow, first one deleted by my hotshot header, then a foot or so of pipe then a long glasspack. Then the rest just be pipe all mandrel bent, no muffler because I perfer the small tip exhaust. With those huge mufflers they are really just short glasspacks which i didnt realize until my exhaust came in the mail forever ago. Hope that helped.

 

OBX Headers come with their own flex pipe assembly I'm pretty sure.

As for replacing the cat, thats your call. Stock cats flow well enough not to warrant the extra money. Going from stock cat to no cat is ~2whp on N/A cars, if that, so I wonder what would be the benefit of going stock cat to high flow.

Stock cat is 2inch inlet/outlet btw. cool.gif