#1  
Old 01-12-2020, 03:22 PM
iceman411's Avatar
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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'71 LeMans Sport convertible under going a frame off restoration
  #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 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight
  #3  
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, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
  #4  
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 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight
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