Dual Port header on Single Port head? Help!

Found a sweet deal on an OBX header on NASIOC, so I went ahead and got it. I was told it would bolt up to just about any N/A Subaru, which it does for mine. I know I'll throw a code with this header, but my brother knows how to shut this off. All the O2 sensor bungs have been welded on where they should be.

 

Only problem is I just found out that my legacy is one of those weird PZEV versions, so it has single exhaust ports on the heads. This exhaust is for dual port heads. Is this going to work? My brother recommended getting some dual port impreza gaskets. Would that make it work? My idea was taking a half inch thick piece of aluminum or stainless steel and having an exhaust shop make a spacer that converts a single port exhaust opening into a dual port without being too restrictive. What should I do?

 

Current exhaust port

 

OEM gasket on new header

I

You might be better off selling that and getting one custom made. A singleport header I would imagine would be easier to make then a more traditional header

I could see that being a lot more costly than this header. I got a really good price on this header. I don't think any companies make singleport aftermarket headers for my car. So IMO, I think I'd be best off modifying the one I have rather than spending money on a custom made one. Maybe if I had the single port parts of my exhaust welded onto my new header, that could work. But would it still be a major restriction if I just got some impreze gaskets?

Dont put those on your car it will hinder any performance you may have. Your only course of action is to had a custom merger welded up to match the stock blob port. Anything less and your engine will struggle to expel exhaust gases.

Dont put those on your car it will hinder any performance you may have. Your only course of action is to had a custom merger welded up to match the stock blob port. Anything less and your engine will struggle to expel exhaust gases.

 

Or maybe I could have an exhaust shop cut out all that metal in between the two pipes and weld it closed on the outside. That way, this header isn't blocking any exhaust gasses, but redirecting the flow of it.

Is the exhaust port on the head actual a big single oval and the exhaust steams from the cylinders merge in the head? Or is there 2 holes and the stock manifold just captures both streams in a single oval pipe?

Is the exhaust port on the head actual a big single oval and the exhaust steams from the cylinders merge in the head? Or is there 2 holes and the stock manifold just captures both streams in a single oval pipe?

 

Yes, the exhaust port on the head is just one oval in which exhaust steams merge. And the stock header has this same oval shape for each head.

Yeah, I wouldnt bother. Looks like you will be cutting off 50% of the cross-sectional area.

My brother says LULZ.

What are you looking to gain from all this work

What are you looking to gain from all this work

 

Respect? Self worth? An lgt? Failing miserably at all points

What are you looking to gain from all this work

Maybe just the boxer rumble?

For seriously, why?

For seriously, why?

 

Why not?

You'll probably have to sell the manifolds you bought and have a custom setup made for you

You'll probably have to sell the manifolds you bought and have a custom setup made for you

 

Yep, so far that seems to be the consensus on here.

I was going to recommend the Rallisport header but I noticed it says for 06+...

 

http://rallisportracing.com/Products.html

You'll probably have to sell the manifolds you bought and have a custom setup made for you

 

stop being helpful

I could see that being a lot more costly than this header. I got a really good price on this header.

 

I could get a good price on 14 inch rims and used motor oil doesn't mean I can use it

My buddy had this same exact problem on an 05 pzev legacy. Heres what we did.

 

Had a machine shop make a flange based on the gasket for the pzev model out of stainless steel since that's what his headers were made of.

 

Then this isn't exactly ideal but overall worked. We had another buddy who could weld stainless weld the flanges to the top of the other flanges. Then he cut about an inch down in the center of the dual ports, cut the outside right off the flange and pushed the two together a little bit. Then welded the crap out of it. Little dremel work and redecked the top of the flange, previously we measured the distance the factory o2 bungs relative to the manifold flange. He welded bungs at those distances a total of 4 on the header. Finally he pressure tested for any leaks.

How I had in my mind was to make a jig and basically remake the header back to the single pipe using the collector already on it modified to fit the flange we had made at the machine shop.

He did whatever was easier for him and would still work good.

 

He also had to get the legacy gt high flow cat. He used the borla replicas.

 

Finally we had to make a little spacer made from the end of the factory cat pipe and a standard flange we bought from an exhaust shop down the street.

 

Results are pretty good. He runs a smaller resonator and factory cans and it sounds pretty good.

 

Finally heres some pics of the header and cat, notice the o2 sensors already in the header. O2 sensor wiring fit just like stock no extenders needed.

 

We also had to make a o2 sensor spacer for the o2 after the cat from a couple of spark plug defoulers to keep the CEL off. This was about a year ago and still no issues.

My buddy had this same exact problem on an 05 pzev legacy. Heres what we did.

 

Had a machine shop make a flange based on the gasket for the pzev model out of stainless steel since that's what his headers were made of.

 

Then this isn't exactly ideal but overall worked. We had another buddy who could weld stainless weld the flanges to the top of the other flanges. Then he cut about an inch down in the center of the dual ports, cut the outside right off the flange and pushed the two together a little bit. Then welded the crap out of it. Little dremel work and redecked the top of the flange, previously we measured the distance the factory o2 bungs relative to the manifold flange. He welded bungs at those distances a total of 4 on the header. Finally he pressure tested for any leaks.

How I had in my mind was to make a jig and basically remake the header back to the single pipe using the collector already on it modified to fit the flange we had made at the machine shop.

He did whatever was easier for him and would still work good.

 

He also had to get the legacy gt high flow cat. He used the borla replicas.

 

Finally we had to make a little spacer made from the end of the factory cat pipe and a standard flange we bought from an exhaust shop down the street.

 

Results are pretty good. He runs a smaller resonator and factory cans and it sounds pretty good.

 

Finally heres some pics of the header and cat, notice the o2 sensors already in the header. O2 sensor wiring fit just like stock no extenders needed.

 

We also had to make a o2 sensor spacer for the o2 after the cat from a couple of spark plug defoulers to keep the CEL off. This was about a year ago and still no issues.

Hey what headers are those? Did they fit right on? I have the same exact exhaust setup that he has and I would like a rumble more than anything now that I know it HAS been done before on our setups

Hey what headers are those? Did they fit right on? I have the same exact exhaust setup that he has and I would like a rumble more than anything now that I know it HAS been done before on our setups

 

http://www.ebay.com/itm/111108346942

pretty much that. He bought the cheap eBay headers since they were gonna get cut up but I think he bought the borla high flow cat.

Looks like the same exact header he bought.

Instead of the spacer I believe I read somewhere if you use the 06-09 midpipe the little adapter isn't needed. If not I think that adapter costed about $4 to make with some welding involved which we did ourselves since it was steel and not stainless.

So I should buy this whole set or just get headers that look exactly like this and get a separate midpipe then? These headers in particular look stainless not steel