I have an '02 Protege 5, that I love (check the pic) but the manifold has a HUGE cat on the downpipe with an o2 sensor above and below it. I need to know if and how I could replace this with a header to get my exhaust singing and free up some horses. I have already heard conflicting advice about legality and loss of back presure etc. So if anyone has tried this or knows anything I could really do with some help.

 

What state are you located in? That should be something to consider befor even modifing the exhaust, header, ect. cause that all has to do with your emissions. Now if that is not the problem (state emissions) then I would say then putting in headers should be no problem.
Can you explain to me about the leagal situation?
Also how wide is your exhaust? If its over a certain diameter then this can cause loss of back pressure.

 

try www.essentialspeed.com

 

Thanks guys, I tried the "super street" board before this one and just got a bunch of prepubescent kids babbling about useless crap.
I found a nice 4 into 1 piece at essentialspeed.com.
Out of curiosity, where do I ask about the emissions laws? I live in Ohio.

 

Gotta love those booger-nosed kids that think wings 2 feet wider than the whole car give you 100HP. ba ha ha

 

PLEASE,PLEASE!!! don't start with the whole "backpressure" thing again....Backpressure does not benefit power in any way...

 

hey "macdaddy" I think you might want to check out super streets message board. They might have some advice on updating those 14"s.

 

i have the bosal header made for the 4cyl probe/mx6

 

Phantom: does that exclude the cat on your car?
What state are you in?

 

Be very careful if you're in one of the Ohio counties that has E-check. They check to see if the emissions devices are still installed before they emissions check your car. If the cat is missing and you fail the test (likely), you have to bring it in compliance before you can renew your plates. There are only a few counties with E-check now, but they keep talking about expanding it.

 

there are a few that make a header for the p5
AWR
Racing Mazda
Wagner Motorsports
...and a few more. AWR's is pricey...racing mazda is hard to get in contact with...and wagner's won't cut out your first cat.

 

Neither will EssentialSPEED's shorty "bundle of snakes" header. It's equal-length--important for equal exhaust pulses and max extraction efficiency--and leaves intact both cats. It's the most expensive of the three ESPEED headers amd more than Wagner's, but most importantly, it also drops the power band about 700 revs. This means more midrange grunt.

I have one coming from Kevin this week. As soon as it's installed, I'll dyno it and let you know the WHP and torque #s compared to my baseline pulls.

Forget a 4/1 header--all it does is add at the top end. A 4/2/1 will give you a better squeeze in upper mids, but the shorty tuned header should help lower down and still give you, at least as much, factory top-end--probably more if my experience with shorties tells me anything.

Don't pull the cats. It's illegal in any state where emission testing is required and the cats draw little in the way of power. Stock exhaust manifolds and exhaust systems suck out much more.

 

I am not sure about ohio..laws..your best checking that out before doing any exhaust work..here in nj..they have the sniffer & obd II test..they dont' check for cats..

Anywayz...I had a header on my ride before i went turbo..

Got it off ebay..it was a 4-2-1...it's was really nice..but it eliminated both cats...

Back pressure is needed on non turbo cars..tq gets you going...and hp keeps you moving at higher mph!

If you lose both cats..like i did..your car will be very very loud..even raspy sounding..like those civic's!

My suggestion to you..is to get a 4-2-1 header..and throw on a high flow cat..and you should be ok!

G/Luck

Chas

 

OK...im going to say this again, but if this misinformation continues i will lock this thread. Backpressure is not necessary on turbo or non-turbo cars. This is an old and widely beleived fallacy but it is not true. Back pressure is sometimes existant on exhaust systems, because it is the best FLOW with available materials. When choosing an exhaust for performance purposes, you need the highest flow available without losing exhaust velocity. This is why a 3" exhaust doesnt work on NA cars...at 3" the exhaust starts to lose velocity. Backpressure is just what it says, pressure created in the exhaust pulse because the the exhaust cannot escape fast enough...for example an 2.5" exhaust is usually a good size on an NA application, and it may retain some back pressure, but the back pressure is not creating torque...the problem is the maximum size you could go before losing exhaust velocity might be 2.57 " or 2.59", but they dont make exhaust piping in that size and it wouldnt be cost effective to fabricate it in that size....If anyone needs further elaboration on this and has a valid question on this subject thats fine, but if you try and come back with some crap like "nuh-uh, backpressure=torque" the i will lock this thread

 

Wow dude..Chill out..why you wanna lock a thread..people are discussing their point of views!

You are correct about back pressure..But the truth is this!

When i had my header on my car..I had NO CATS AT ALL..

I had a silencer in..and the car pulled nicely when leaving the line..

But when i removed the silencer..the car had to be rev harder..and didn't pull as quickly off the line!

So please explain!

B/c i happen to believe that back pressure was helping me off the line due to the silencer!

Chas