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Discussion Starter #1
Last weekend 1loudfocus and i installed the OBX header. Ive been looking at catback exhaust systems but i wasnt sure what size the outlet was on the header.

Oh man this header has a junk flex pipe. It doesnt stay at 2.5 once it leaves the header. It goes from 2.5 on the inlet side of the flex pipe and then comes out 2.25"

I wonder if the FSwerks flex pipe will fit the OBX header? I think ide prefer to have it stay at 2.5" all the way back.

Any thoughts?



This is the left over "MTX" flex pipe that comes with the header kit on ebay.
 

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GT40 all the things!
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Take it to a muffler shop. Couldn't cost that much to weld a 2.5" pipe in place.
 

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Discussion Starter #4
Well i was thinking about just having a new flex pipe put on and then everything behind it be 2.5 and then have them build it from there back.

I didnt have the money for the header AND the custom catback so thats what im planning next but i wasnt sure what size i needed. Tom said to put 2.5" all the way back but i wasnt sure the size of it so i thought hey i have that MTX flex pipe left over and while i was looking at it it didnt look the same on both sides.

Why would they do that? is it the backflow or something or so it better matches the stock catback setup?
 

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With the mods you have it will flow more then enough.
 

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w/ my magic bag
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I'd just use it the way it is. 2.25 is good enough, you will never notice it. What size is your primary pipe on the OBX header? If you took this header to a shop & told them to put this on, you wouldn't notice, going from 2.5 to 2.25 would you? I'd be more concerned about the lenght & size of the header. That's where the gases are the hottest, coming out of the head.
 

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Discussion Starter #7
I'd just use it the way it is. 2.25 is good enough, you will never notice it. What size is your primary pipe on the OBX header? If you took this header to a shop & told them to put this on, you wouldn't notice, going from 2.5 to 2.25 would you? I'd be more concerned about the lenght & size of the header. That's where the gases are the hottest, coming out of the head.
Its 2.5 at the outlet.

well ill see if i can get the flex fixed when i have the rest of the exhaust from the flex back installed.
 

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w/ my magic bag
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Primary pipe vs lenght.

Its 2.5 at the outlet.

well ill see if i can get the flex fixed when i have the rest of the exhaust from the flex back installed.
^^^ That's the collector, I met the primary pipe, that's welded to your header flange= you have 4 of them going into your collector. I alway's figured out the primary pipe diameter & the over all lenght. Come's down to gearing, auto or manuel, & weight of car.
 

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Discussion Starter #9
^^^ That's the collector, I met the primary pipe, that's welded to your header flange= you have 4 of them going into your collector. I alway's figured out the primary pipe diameter & the over all lenght. Come's down to gearing, auto or manuel, & weight of car.
I dont know the length

Primary Port Diameter: 1.75 Inch I.D.
2.50" Collector.
100% T304 Stainless Steel..
Flange Thickness:3/8 Inch.
Runner Wall Thickness: 16 Gauge(1.5mm)
CNC machine flanges with TIG and MIG welded construction
 

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How's it sound & run now? Any problem's w/ the install of the header itself? I'm doing this Thrusday w/ a F/W's header.
 

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Discussion Starter #11
Well we couldnt get to the bolts for the stock flex pipe. They are welded on one side and you cant get tp the other side you have to take the stock one out with the flex pipe on it.

We couldnt get the OBX down into the spot with the flex pipe on it. Im not sure why, maybe because mine is ATX? Everyone else said to drop it in with the flex pipe on but that didnt work. Maybe these newer ones have slower larger bends?

Once we got the header on we put a few bolts on to hold it there and then put the flex pipe on from the bottom. Since you can get to both sides of the new bolts we were able to get it on.

Mine is ATX and it had a bracket that held it to the engine. That didnt line up with both bolts. I figure after i drive it a while it might loosen up the flex pipe a little and we can get that plate to go on with BOTH bolts. If not when i get the rest of the exhaust built ill see if they can drill or weld it or something.

I should have that done in a few more weeks. Still saving for the back half.

Like i said in another post. It was pretty quiet stock and removine the lunchbox was about 2 clicks louder. The header is now about 2 more clicks louder. To me it sounds like a car the muffler fell off. Some cars have a sound with the cat and resonator still on but the muffler fell off mine sounds about like that now. Not very good. Its a little louder and raspy.

We took off all the 02 sensors before we took it out. We put the 2 back in after it was on. I didnt put my second bung in a good spot. Its tight up against the firewall and bent over at a 90 which might shorten the life of the wideband.

I hope the wideband just gets me threw the tune.

If you havnt welded your wideband bung on yet ide say put it on the flex pipe later or wait till its on and just finger tighten the head bolts and find a better location theni did. This is with the OBX which only has 1 bung stock. I think yours is the FSWerks and i think its all setup.

Out of all the things i wish ide done over on this install it was that.

We only had 2 torque wrenches and both were pretty long. We torqued the first 3 i believe but then hand tightened the rest but we tighted them in the order the specs say atleast.

The head nuts are soft so if you start to over tighten them be careful they tend to stick into your socket.

I think 45 lbs is all they can take and the corners of the nut start to fold over.

We had one nut stick on the bolt and it backed the bolt out of the head (during removal of the stock manifold) Lucky it backed out a few turns before it loosned the bolt because the new header has alot thicker plate. They need to be backed out a few turns for the new plate. Its twice as thick.

We questioned using the stock manifold gasket but then realized the header has alot bigger primarys and using the stock gasket would just block the primary flow. It still looked good though

Hope some of this info is useful?
 

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That's what I find is the bracket from the header to the back of the engine didn't match up, so I zipped off the welded nut's & ablonged the hole's further in more, you should add this for support of the header. & I used the original heat shield covering the alternator, to keep some heat off it. & the bracket on the driver's side where the O2 senser's connect together, was hitting the front part of the header, so I took that off. I had to exstend the stealth muffler 4.00'' or so to fit up to my Borla exhaust. I just used a racheting wrench top & bottom & a inverted torx to tighten a couple of the stud's that were comeing out w/ the nut's. I took me 4hr's to do this & some people do it in 2, Ok Iwas was slow, but it's done right, the 1st time. Thanx for your input BowerR64
 

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Discussion Starter #13
How did you mount the stock heatshields?

We got one of the screws to go in but not both i just hope it holds till i get the rest of the exhaust finished.

Man running it with just the header and the stock catback it rattles more then ever. Im hearing stuff in the dash rattle now, stuff in the trunk it really sounds like the car is falling apart now.
 

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Should'nt be rattling. Mine didn't when I had the stock catback.
 

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Discussion Starter #15
Should'nt be rattling. Mine didn't when I had the stock catback.
Well i took my lunchbox off, its just hitting tones that are resonating inside the car ratteling stuff in the car or the bumper or something.
 

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Stock heat shield's

How did you mount the stock heatshields?

We got one of the screws to go in but not both i just hope it holds till i get the rest of the exhaust finished.

Man running it with just the header and the stock catback it rattles more then ever. Im hearing stuff in the dash rattle now, stuff in the trunk it really sounds like the car is falling apart now.
The heat shield on the 23's are 4 piece's all hooked together w/ tap's. I used the origanal one covering the alt. to keep some of the heat off it. I laid that piece in 1st & than put the header in, whole holding that alt. insulter in & tighten down the header in sequeal or tighten down order at 41lbs. I used 3 black tie rap's.
 
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