OBX header install with lots of pics
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
OBX header install with lots of pics
So thought I would add the install process for me with these headers. To start with I had to remove the normal stuff. Plugs, starter, Steering shaft, Blower box assembly and my driver side coolant sensor.
Next I found that both sides went in pretty easy from the bottom. I could not get either side in from the top as I found a few others had. I also had to grind a little notch off a tab on the tranny that holds up the plastic flywheel cover to allow the header to slip by on the drivers side. Probably could have lifted the motor a little but this was easier for me.
I also had the typical bolt holes not lining up perfect on the heads. I just used a die grinder with a tungsten carbide bit to open the holes up. It was a pain to get right. Taking them in and out of the car a hundred times sucked.
I did grind a little off of the driver side control arm mount for clearance. I also had to grind the tranny cross member for clearance of the y pipe tubes.
Now onto the pics..
Next I found that both sides went in pretty easy from the bottom. I could not get either side in from the top as I found a few others had. I also had to grind a little notch off a tab on the tranny that holds up the plastic flywheel cover to allow the header to slip by on the drivers side. Probably could have lifted the motor a little but this was easier for me.
I also had the typical bolt holes not lining up perfect on the heads. I just used a die grinder with a tungsten carbide bit to open the holes up. It was a pain to get right. Taking them in and out of the car a hundred times sucked.
I did grind a little off of the driver side control arm mount for clearance. I also had to grind the tranny cross member for clearance of the y pipe tubes.
Now onto the pics..
Last edited by seiplentz; Mar 7, 2015 at 02:14 PM.
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Joined: Aug 2008
Posts: 85
Likes: 25
From: Appleton, WI
Car: 73RS, 85 Iroc, 11 GT
Engine: 383FI, 406 FI, 5.0
Transmission: TKX, TKO600
Axle/Gears: 10 Bolt 3.73s, Strange 12 bolt 3.73
Re: OBX header install with lots of pics
I can't believe they haven't made any improvements on these. Make sure it is not just the bolt holes that are off. I had to have the flange cut cause one of the tubes wasn't lined up well with the port in the head. Finally I said heck with it and went with a set of Hawks Stainless works . Learned my lesson
Junior Member

Joined: Oct 2005
Posts: 56
Likes: 4
From: In Central Illinois
Car: '88 Firebird Formula 350
Engine: L98 TPI 350
Transmission: 700R-4
Re: OBX header install with lots of pics
I've been wanting to order this set. How long did your install take? How did the rest of the install turn out? How much did you have to modify the exhaust to mate up to the supplied parts?
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Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Re: OBX header install with lots of pics
My install probably took me 30 hours as I took my time and I'm not a mechanic. Not sure about what you mean by mate up. I did not use any of the remaining exhaust. After the y-pipe that comes with it I added a pypes muffler and a 3" turn down. I will be adding the rest over the axle and back when I have more time. Spring is here and I want to drive it.
Junior Member

Joined: Oct 2005
Posts: 56
Likes: 4
From: In Central Illinois
Car: '88 Firebird Formula 350
Engine: L98 TPI 350
Transmission: 700R-4
Re: OBX header install with lots of pics
My install probably took me 30 hours as I took my time and I'm not a mechanic. Not sure about what you mean by mate up. I did not use any of the remaining exhaust. After the y-pipe that comes with it I added a pypes muffler and a 3" turn down. I will be adding the rest over the axle and back when I have more time. Spring is here and I want to drive it.
I'm curious about the sound too but since you added a turn down I'm assuming it's louder than before.
Junior Member
Joined: Mar 2009
Posts: 46
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From: Indiana
Car: 91 Camaro
Engine: 355 Carb
Transmission: 5 speed
Axle/Gears: 342 Posi
Re: OBX header install with lots of pics
Should have just went with "Dyno Don" headers.Mine fit perfectly and no problems with install. He's a member, look him up.
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Re: OBX header install with lots of pics
I am quite aware of his headers. I wanted stainless and long tubes. There only 2 options and it wasn't a big deal for the cost. All headers require some sort of work. A little filing of some bolt holes big deal.
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Re: OBX header install with lots of pics
I can't blame you for wanting to drive it now rather than later. I was planning to use the rest of the exhaust if possible so I wanted to know if you had to modify it much to fit it together.
I'm curious about the sound too but since you added a turn down I'm assuming it's louder than before.
I'm curious about the sound too but since you added a turn down I'm assuming it's louder than before.
Flowmaster before
Pypes after
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Posts: 263
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From: Pennslyvania
Car: 1984 camaro Z28
Engine: 355 SBC
Transmission: 700 r-4
Axle/Gears: Strange 3:73 posi
Re: OBX header install with lots of pics
Do you happen to have a picture of the y-pipe installed , I'm having a issue lining up the passenger side and wanna make sure I have the pipes in the right spot before I hit it with a hammer.
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Member
iTrader: (1)
Joined: Jun 2009
Posts: 263
Likes: 0
From: Pennslyvania
Car: 1984 camaro Z28
Engine: 355 SBC
Transmission: 700 r-4
Axle/Gears: Strange 3:73 posi
Re: OBX header install with lots of pics
Thanks a lot that's exactly what I was looking for . I'm probably gonna have to message the passenger pipe a little to clear the umi crossmember I have .
Thread Starter
Joined: May 2003
Posts: 445
Likes: 6
From: Delco pa
Car: 85 Z28
Engine: GMPP 350 HSR
Transmission: 700R4
Axle/Gears: 4th gen 3.42 Posi LS1
Re: OBX header install with lots of pics
Member
iTrader: (1)
Joined: Jun 2009
Posts: 263
Likes: 0
From: Pennslyvania
Car: 1984 camaro Z28
Engine: 355 SBC
Transmission: 700 r-4
Axle/Gears: Strange 3:73 posi
Re: OBX header install with lots of pics
Gotta take it to an exhaust shop , I'll take some pics when it's done .
Senior Member

Joined: Feb 2003
Posts: 644
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From: Fleming Island, FL
Car: 1992 Formula 350
Engine: 5.7 L98
Transmission: 700R4
Member
iTrader: (1)
Joined: Jun 2009
Posts: 263
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From: Pennslyvania
Car: 1984 camaro Z28
Engine: 355 SBC
Transmission: 700 r-4
Axle/Gears: Strange 3:73 posi
Re: OBX header install with lots of pics
Exhaust guy said he can make the y pipe work but the collector tube is touching the trans 😢
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From: MA
Car: 1989 IrocZ
Engine: 421 Dart Stroker
Transmission: 4L60E Cahall Performance Built
Axle/Gears: Midwest Chassis Fab 9/ 3.55 gears
Re: OBX header install with lots of pics
I can't believe they haven't made any improvements on these. Make sure it is not just the bolt holes that are off. I had to have the flange cut cause one of the tubes wasn't lined up well with the port in the head. Finally I said heck with it and went with a set of Hawks Stainless works . Learned my lesson
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