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Old 01-12-2020, 03:22 PM
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iceman411 iceman411 is offline
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Location: Grand Rapids, Michigan
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Default 71 GTO 3”exhaust recommendations....?

Wow, been a few years since I looked at Pypes and their 3” exhaust kits. Seems to me that they made a valance cut out kit for these cars and the 3” splitters as well. Not so today. I’ve run this engine I plan to use with a Dr Gas 3.5” x pipe into 3” Violators in a street raced ‘69 GTO and it was loud with the pipes dumping at the axle. Engine is a Kauffman spec’d 455 stroker wit ported e heads making 600 horse or so. That was a few years ago. Now I’m putting my ‘71 convertible together and getting my wish list going and discover they no longer make a valance exit 3” kit.... Is there a procedure in getting the standard 3” Pypes kit to fit the valance year cars or is there a better option? Mainly building a cruiser yet not certain I want to choke down the exhaust for the performance to suffer. I’m running DOUGS round port headers as well, which have a 3.5” collector.
Is there another exhaust kit brand worth considering? I’ve used 3 2.5”Pypes kits for other projects in the past and the fit and quality can spoil you quickly....

Thoughts anyone? I can tig weld and fabricate, just not interested in doing a whole exhaust that way. Modifications are a way of life, even today to get it right....

Thanks, Mike...

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  #2  
Old 01-12-2020, 06:32 PM
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leeklm leeklm is offline
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Run a 3" X and mid pipe. Mufflers with a 3" input and 2.25 or 2.50 exit and tail pipes.
You will not notice the minuscule (if any) power loss by running smaller tail pipes, especially on a cruiser.

I had the same setup with 600hp in my 73 gto and worked great, and still pushed the heavy beast to 11.3 qtr mile.

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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 305 CFM and Old Faithful 2.0 from SD Performance. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 1" open spacer. TH400 w/low gear set. Ford 9" w/3.50 gears. Full 3" exhaust with H pipe, 14" Ultraflow. Best run to date: 1.52 60ft, 6.729 @ 103mph, 10.556 @128.27 mph. Approx 3,320 race weight
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Old 01-15-2020, 05:05 PM
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AG AG is offline
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Do you have a rollbar in your '68 Bird?

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1967 Firechicken, 461, Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3520#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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Old 01-15-2020, 05:27 PM
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leeklm leeklm is offline
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Quote:
Originally Posted by AG View Post
Do you have a rollbar in your '68 Bird?
Yes, 6pt with bars extended to rear frame rails and swing out door bars. I usually leave the door bars out when cruising around town. Just used mild steel built to NHRA guidelines.

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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 305 CFM and Old Faithful 2.0 from SD Performance. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 1" open spacer. TH400 w/low gear set. Ford 9" w/3.50 gears. Full 3" exhaust with H pipe, 14" Ultraflow. Best run to date: 1.52 60ft, 6.729 @ 103mph, 10.556 @128.27 mph. Approx 3,320 race weight
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