I think I'm finally ready to start purchasing everything needed for the duratec headers and custom everything back to Mina mufflers.

I just need some advice as to what to pick up. Should I buy the 2.5l or the 3.0l duratec headers? My motor is the 2.5l...

Also, I saw a post on the s type forums a dude was taking about he ran the headers to a Dodge v8 2 into 1 high flow cat then custom piping back to some other brand mufflers but he said it was extremely loud in the cabin. He said he did this to an x type... I'm OK with some noise but not if it's deafening.

I was thinking of keeping the resonator to quiet it down a bit. What do you think?

Basically just looking for some purchase advise and some overall opinions of what direction I should go with this. I'm thinking I'll be one of the few to do it so I'm amped about it.

Thanks folks!

 

I would say to go with the 2.5L headers as they are going to be tuned slightly differently than the 3.0L headers and you may get some more power out that way.

As for the resonator, I think that is really going to depend on the mufflers. In the case of the Mina mufflers, I would leave the resonator out and just go with straight tube back to the mufflers. I would recommend installing an X pipe immediately downstream of the cats to help even out the exhaust flow. Then I would also recommend not exceeding 2" piping if you are running true dual pipes and not more than 2.25" piping if running a single pipe back. Going much bigger than this may lead to insufficient back pressure which can result in CEL hell.

 

Right on, thanks.

Do you think I'll get any CEL at all?

Honestly, I'm not sure what the set up will be. Should it be headers with each side having it's own cat or should it be headers ran into a single cat? And if it's 2 cats would I then install the x pipe with 2 pipes running back to the mufflers? If it's one cat being a 2 into 1 would I then have a single pipe back to a split into the 2 mufflers? Lol sorry I've never had a custom exhaust on anything!

I was thinking that almost mimicking the current set up but with freer flowing materials would be best. Is that not a true assessment?

As for cats, am I looking for any duratec performance cats that suit my set up?

 

X-TYpe, how you design the exhaust system is up to you. All of what you said is correct. You can do 1 cat, 2 cats, 1 exhaust pipe, 2 pipes, 1 muffler, 2 mufflers. In theory, running 2 of everything is better (assuming the same size components) as each pipe will then carry half the flow, which then means that the pressure drop is 1/4 what it is with the single pipe. But, something as simple as going to a slightly larger pipe over comes this.

You will find that there are tons of thoughts on this and as to which design is better.

 

Thermo, of course, has hit the nail on the head with great advice. My question is, where are you getting headers from? I have a set from OBX for a 2.5 contour/cougar V6 still waiting to be installed. I'm in FL so I don't "need" cats so I won't be installing any. My plain is to run a 2 inch pipe for each header back to my mina mufflers with an x pipe around where the center of the driveshaft is. If I was going to install cats, and I had the funds to buy two of them, I would run two, one off each header, right next to each other and relatively close to the engine since heat is good for cats. In my search for headers, this goes all the way back to owning a SVT contour, I found that the guys who have a 3.0 use the same headers as the guys with the 2.5 and I've never actually seen a company advertise headers for a 2.5 or a 3.0, just the 2.5 since the contours/cougars only came with a 2.5 and people swap 3.0s into them. One cat and one bigger pipe that splits over the axle will also work, and frankly I think the biggest difference between a true duel setup and building a bigger more free flowing stock single pipe set up will be the sound. I'm going with the true duel setup, just because really. I've debated with myself over both many times haha. You must post pics and videos after you have this done though. I haven't seen many people... anyone actually... on here do this yet. Oh, as for the check engine light going on, I think that's anyone guess. It might not, but, it might.

 

Yeah I was thinking the OBX as well. They're pretty much all I could find other than the MSDS ones but they're crazy pricey. Is the y pipe that comes with the OBX going to bolt in without clearance issues? If so I think I'm just going to do a single 2 or 2.25inch pipe back to a split into the Mina's with a high flow cat right after the header assembly. My reasoning for going with a cat is to try to eliminate the CEL. I might be wrong (probably) but I'm thinking If all the o2 sensors go back in factory locations in relation to the exhaust system, the computer might not recognize any change mechanically and relearn/recalibrate based on the new information provided. I'm only thinking this because our cars seem to do a lot of self adjusting and regulating.

When I did the whole port match thing on the intake it seemed like after a hundred miles or so, even the shift points were a little different as if the computer adjusted them in relation to the slight increase in performance.

I think this is why I'm going to do a single pipe and also why I'm going to throw in a cat even though I don't "need" one. We'll see how it goes. The shop who did my suspension work is going to do the exhaust also. They do great work but mainly build sti's and evo's (currently selling a shop built 550whp sti) but they love the x type and were excited to do the suspension and are super stoked to do the exhaust.

I'll put pictures up when it's done. I ordered the Mina's yesterday and about to order the headers and cat right now. Once I get all the parts in I'll schedule the install. It's my family DD so hopefully it's not out of commission for too long, otherwise my lady will have my *** haha. Btw, she loves the car too. She loves the attention she gets driving it. Hot chick in a modified jag...

 

From what I've seen it seems as though the y pipe is the same shape on the contour headers as the stock x type's pipe so I don't think there will be any problems there.

 

Thanks man. Yeah I figured it out eventually lol. Seems as if I'm a week late on wanting to start this haha. The obx are no longer being sold through the only place I've been able to find them, racingpartdepot.com. Last week they said in stock. The day I wanted to order they said out of stock and now you can't even find the part on their site lol but I'm on to some lightly used msds off the neco forums but they don't come with the y pipe. Any suggestions as to where to find one?

 

Found my own answer haha. Msds sells the parts individually both coated and non. I'm ordering the y pipe right now, uncoated. I'll do that myself. Things are rolling!

Going with a 2.25inch all the way back. What size inlet is the Mina mufflers?

 

Completely second guessing my design now. I'm realizing there is 4 o2 sensors but the single cat and pipe set up I was planning only has room for 1 down stream lambda and 1 in each manifold.

What happens to that 4th one if I keep the set up? I've read about o2 emulators and what not. What do you think that would do to the x types computer?

I have no problem skipping the y pipe and running duals all the way back with 2 cats involved but I wanted to try the single pipe set up just because justink is going to do the duals eventually and I wanted it to be different so we could compare.

Is there a way to keep 4 o2's with only 1 cat? And also, is there a way to run 2 cats but only a single pipe? Or does that last question seem stupid? Haha

 

Mentality, in theory, you can put the 2 downstream O2 sensors side by side, that way you maintain the 4 sensors. But, this can possibly lead to issues because the computer will alter the air to fuel mixture and then expects a change to be seen at the downstream O2 sensor a finite amount of time later. With having the sensors in the same pipe, the computer may see things as being "strange" since it will see a change on a given cylinder on both downstream O2 sensors. I am not sure how the computer would handle that.

As for running 2 cats on a single pipe, sure, you can do that, a lot of modern day vehicles run 4 cats with 2 cats on each header. So, yes, it can be done. But, you are still in the problem I mention above.

 

Looks like I'll be running the dual set up as well condidering I'm trying to almost mimick the stock set up.

You're right, thermo, that if the downstream 02's are reading the same thing for both banks but the upstreams have their own seperate readings, it will for sure trip the CEL because the computer will have no idea which bank to adjust mixtures in if it doesn't know which bank is giving the problems.

I might still try to do a single pipe after the dual cat set up and then open it back up to 2 at the mufflers but that almost seems pointless. I might as well just do the duals all the way back.

Should I do 2" since I'm doing duals now or will the 2.25" still be doable? I already ordered the cat I thought I'd use but it's in a 2.25. I want to just order another rather than deal with returning it...

Thanks for the help so far!

 

Mentality, I would think that you can be safe with running dual 2.25" pipes. I would not go bigger and I would think about running a 70 series muffler just to add some backpressure back into the system. The exhaust will be moving fairly slow with the 2.25" pipes, so, the mufflers will not have to work as hard to do their job and therefore should still give you a fair amount of volume. You can try running a 50 series muffler, but I would start to wonder if you would be getting a check engine light or not. Hard to say. I am not sure how open you can get the exhaust before it starts giving you grief.

 

first off let me just say I know little about muffler design but could you use a 2.25 - 2 reducer off the cats and run 2 inch back?

Marwil Prod 2.25" I.D. x 2.00" O.D. Reducer 548502: Get the best Straight Reducing Adapters at Advance Auto Parts

 

The mina's are meant to slip over the stock 2 inch pipes, one of the reasons I want to go with 2 inch. Another reason is space is tight around the rear subframe and with how low my car is I NEED the exhaust to tuck into the trans tunnel and rear subframe. I wish I could help with the o2s more but until you or I do this project I have no clue what the computer would do. That's one of the reasons my headers have been sitting in the box for 6 months or so haha. I did buy some "mil eliminators" from nautilus performance just in case but I don't really want to trick the computer. I did some research on tuning the ECU and if we were in the UK there are many places that offer tuning. I did find a place in Miami (3 hours from me) that is a distributed/tuner for one of the UK based companies so one day, probably after I get a 3.0 to swap in, I'm going to install the headers and whatnot (probably have the heads ported/valve job) and see if they really can tune the x type's ECU, and if they have an awd dyno to do it on. If so I'm going to take the car to them to tune it. I sure wish someone made a hand held programmer for the X, but I emailed just about everyone I could think of that makes them, nothing for the X. I had one for my mustang and it was simple to tune the ECU for headers and no cats with no CEL. I want to get as close to 300hp as I can, transfer case be dammed. I have a plan for that thing too. Eventually my car will be a bit of a track beast. My mustang only had about 330 to the wheels and weighed just 60lbs less than the X type, and my stang would run low 13s with traction problems and topped out at like 150mph. Plenty fast for my X type haha.

 

Haha yeah that's what I'm trying to do as well. I'm going to build the most powerful x type that I can and I had the same thought about the transfer case, Eff IT! Haha. Nobody has really pushed the transfer case to the limits with power. Who knows if it'll actually fail? (I'm sure it will but you can't speculate, only prove it!)

My fiance wants a newer x type so I'm going to start looking for a cleaner, lower mile one here pretty soon so when that one comes along I'll swap over everything I've done so far and then I'll have guinea pig parts to play with. I'll get the 3.0 this time but only crappy thing with that is my project motor is a 2.5 but I'll just have to have it stroked and bored I've been reading a ton about these motors and I've started to realize there is actually plenty of potential with these duratecs. During my research I did find the place in the UK you're talking about who tunes the x. Sucks there isn't anything solid in the states.

Yes Paul that will work but I'm going to just return the 2.25 I ordered. I've already ordered the 2 high flows I need and I'm going with a 2 inch set up. Seems like justink and I will have pretty much the same set up except I'll have cats involved.

 

I've seen 3.0 swapped contours with a turbo and not much else running 400hp. Noble used to use a twin turbo 3.0 that made over 400 in their first cars. Nautilus sells blocks up to 4.0 I believe but they are like 4k just for the block. These engines are awesome, and little known. My dream engine build would be a 4.0 sized Duartec with high compression and individual throttle bodies, ported heads, custom cams and balanced internals and whatnot to spin to 8k rpms. Not likely to happen but, you gotta dream big so that when you go to compromise you still end up with something badass haha. the last generation mercury cougars are fwd but you can find them with the 2.5 v6 and a mtx75 5 speed, and they are under 3k lbs in weight. I want one for a beater car. I had a svt contour already.

 

I know I'm the new guy here, and I don't have any credibility yet, but the info below might be worth considering.
Me thinks good idea.
A resonator will not inhibit exhaust flow and will help eliminate any horrible droning sound.
The voltage data compared between upstream and downstream will turn on a CEL. Its not determined by location.
Although I do not know what the tolerance is, its likely preset. Theres nothing to relearn or recalculate for that field.
If theres no cat there then the downstream will determine that the (missing) cat is not doing its job, and throw a CEL.
As mentioned above the downstreams just send a signal to the ECU saying if the cats are ok or not (and if not; turn on a CEL) based on comparing data from the upstreams. There is little variance from them in terms of reading at the ECU once the cat is up to temp.
To the best of my knowledge: they do not tell the ECU to adjust air/fuel ratio. Thats what the upstreams are for.

If I'm correct about the downstream's function, then you could always just not install any sensors downstream, and just splice a resistor of appropriate value into each harness for the two downstream that will give the ECU the voltage reading it wants to keep it happy and keep CELs off.

Or in the above case just install one downstream and trick the other with a resistor spliced in. (I suppose thats what an emulator does)
One upstream will then be comparing data against a reading from a resistor (it will always be ok) and the other with actual data from exhaust gases after the cat. This set up should not cause any problems, and will still function to turn on the CEL if the cat ever goes bad.

 

Are you sure that is the function of the downstream sensors?
I don't think they are there to check if air/fuel ratio changes have been made.

The downstream sensor just puts out a certain voltage. If the cat goes bad then the voltage coming from the downstream sensor will be almost identical to the voltage coming from the upstream; meaning the cat has failed or is missing.
At which point the CEL turns on.

I'm 99.9% sure that is all they do. If you have a source of info that they do something else please let me know.

 

Not sure what kind of gains are expected, but I'm excited to see how this exhaust mod turns out. Since apparently not many people have attempted such a thing.