i have an obx header that i haven't installe yet. i'm waiting to get a testpipe and cat back before i install it. the problem i have is that the outlet on the header has an inside dia of 2 1/4 in. but all the testpipes and afordable catbacks i've found say that they are 3 in.

willa 3 in work?

 

A friend of mine said it should work, because the flanges should be the same. is this true??

 

yes the flanges are the same, but did your "friend" mention that by replacing the cat with a test pipe you'll only see about a 3hp gain? not only that but you'll also be contaminating the environment.

 

only 3 hp???shouldn't it be more because the exhaust is free of the restriction of the cat??

i grew up on classic v8s and want to use some of those same ideas

 

Your lucky to see 3-5hp from a aftermarket exhaust mani for a NA KA. I myself just bought a HOTSHOT from a friend and from what i read on a dyno chart on another forum is the the hotshot proved the most hp out of DC Sports, OBX ect...the guy tested them all with charts.

 

+1

Your only going to see a 1-2whp increase

I also believe HS Runners are 1.25" and the outlet should be 2.5" if I'm not mistake, dont know the OBX size besides the outlet is 2.5" also

this was a test done on a MX-5 (Stock was 104)

 

Not only that but if his engine is OBD2 it will throw a cell and run pig rich.

Who the f$ck filled you with that non sence. HOT SHOT is a good header, but I have a DC sport header, and no one with the HOT shot header has beaten my dyno on the internet.
Besides how did you get that hot shot header? Hot shot has been out of business for over a year.
Got a link?

 

well vinnie your engine is awesome so of course no one is gonna beat your header dyno i know that a header will increase hp but you gotta add other mods to it to get the gains your looking for.... one question vinnie i have a early 95 zenki if i punch out the cat (clogged) will it throw a code for me as well?? i have 2 o2 sensors i believe..?

thanx Eric

 

Yes...
You will need a high flow cat. You can't used a punched cat.

 

okay thanx vinnie

Eric

 

I had in mind that some nice pair of headers would have added maybe 10 hp to a NA KA. from what I have been reading there is only minor hp gains from top brand headers. This is a dumb question but would headers +intake+ exhaust add a significant amount of hp?

 

so many factors determine HP guessing at it is not good just install it tune it dyno it drink beers