#1  
Old 03-06-2023, 02:24 PM
Tarl Tarl is offline
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Join Date: Apr 2001
Location: Boston, MA
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Default Exhuast for 68 Firebird Convertible and ground clearance

Hi All,

I really want to upgrade my current exhaust, its very restricted and drones like crazy right off idle. My only issue is ground clearance as I have to get it into a basement garage a lot as it currently scrapes on the subframe connectors.

It's got a 400 and long branch manifolds, I guess I am down to 2 exhaust kits, Pypes SGF70 X-pipe and Thrush 89021 H-pipe, both 2.5 inches.

I love the Pypes x-pipe system on my Lemans and would like to use it on my Firebird but it seems I might have to lower the convertible brace 3 inches in the front for that system.

Does anyone know if I have to modify the convertible brace for the thrush H-pipe system?

Does anyone have any real world numbers on how much lower my convertible brace would hang using both these systems?

Thanks in advance!

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1968 Firebird convertible 400/4spd
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  #2  
Old 03-06-2023, 05:17 PM
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Formulajones Formulajones is offline
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Posts: 10,794
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I've used both of those systems numerous times on various F and X-bodies. Fitment is excellent if you spend some time with it, and once installed properly you can't even see the system on the car, ground clearance is excellent as a result.

Never installed one on a convertible though. Hotchkiss and BMR both make a brace that has a slight drop down that would make things a little easier.

However I have successfully installed the Pypes SGF70 system making the intermediate pipes tuck up into the trans tunnel pretty far running parallel to the driveshaft to the point that you can't even see the exhaust from the side of the car. It's easier to do this with the SGF70 system because of the "X" and the ability to turn and trim the pipes as well as angle the "X" upward, making the intermediate pipes tuck up further and closer together inside the driveshaft tunnel to some degree. I tend to think it wouldn't be much more effort to get it inside the brace, even if you had to space the brace down slightly.

Don't really have that ability with the Thrush system because the "H" section comes welded together so you're basically stuck with the width and angle it comes with. Not near the wiggle room and adjustability of the SGF70, So there's that to consider.

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  #3  
Old 03-07-2023, 10:49 AM
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XLR8STEVE XLR8STEVE is offline
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Location: Detroit Area
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Sorry no good pics except this one. 68 Conv. Hotchkis brace was great. Fit a 3" system in the car with zero ground clearance issues. I'm sure a 2.5 will fit. On my 2.5 prior to this I had to shim the stock X brace down with a couple washers to clear and not hit the pipes.
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Old 03-08-2023, 12:31 PM
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jwcfbd jwcfbd is offline
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Join Date: Mar 2003
Location: Texas
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I went with Flowmaster 17104 kit for my 67. I also put the Hotckis cross brace on it. The only problem I've ever had was one of the bolt flanges on my headers so I cut the weld and rotated it. See my install here. https://forums.maxperformanceinc.com...d.php?t=423873

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