Aftermarket Exhaust on a 69 GTO - Pontiac GTO Forum
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post #1 of 12 (permalink) Old 06-11-2013, 01:12 PM Thread Starter
 
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Aftermarket Exhaust on a 69 GTO

Hi All,
I just purchased a 1969 Base Model GTO with a 400 and was wondering which exhaust system to purchase. I'm sure there are two schools of thought concerning this question. One being the boost in HP, while the other being the sound. Is it possible to have both? I would prefer a meaner sound over HP being that it's a 400 but if I could have both that would be a bonus. Thanks in advance.

-Todd
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post #2 of 12 (permalink) Old 06-11-2013, 03:31 PM
 
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Flowmaster...sounds great with out being too loud and motor seems to breath good
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post #3 of 12 (permalink) Old 06-11-2013, 04:03 PM
 
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I recommend Dynomax welded ultra-flo, Goerlich Xlerator or Pypes Race-Pro mufflers.

All of these are "straight-through" designs that flow approximately 95% as much as a straight piece of pipe.

They are not as loud as Flowmasters and (in most cars) do not exhibit the drone that you get with most Flowmaster mufflers.

Here is a great page that provides comparisons af these different mufflers on the same car:
Pypes Performance Exhaust - GM Sounds

If your 69 has a high quality, reproduction (stock) system on it (including the 2 different length mufflers), I highly recommend that you take it apart carefully and sell it or keep it for re-sale. The OEM reproduction systems are quite expensive and if yours is one of the good ones, it should be worth at least $200 to someone looking to put an OEM style system on their car.

1968 Pontiac GTO
1983 Pontiac Bonneville (G) wagon
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post #4 of 12 (permalink) Old 06-11-2013, 05:13 PM
 
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I bought the Pypes 2.5" Street-Pro system for my '66 with a 455 and I love it. It was easy to install and the power and sound are unbelievable. Got it at the Pate swap meet at the Texas Motor Speedway and saved the shipping, I did spend an extra $40 (it was $440 total) and got the nicer clamps that Pypes makes. I will eventually weld the system, but used the clamps because it will be coming back off this winter when I do some floor pan and trunk repair.

Randy
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post #5 of 12 (permalink) Old 06-12-2013, 05:03 AM Thread Starter
 
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Awesome! Thanks for the info guys, this put me in the right direction.
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post #6 of 12 (permalink) Old 06-12-2013, 07:29 AM
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Garage
I'm running a Pypes 2 1/2" system on my car with their X-change crossover and RacePro mufflers. According to their literature, those mufflers are their most quiet and also the best flowing. "Quiet" in this case is a relative term. At part throttle, I guess they are quieter than some I've heard but when I hammer it, that's another story.

In this video, which was shot from inside the other car, you can hear when I pull up beside him and when I hit it you can barely hear his car.


Hey Randy! You're in Rowlett? I live in Garland.

Bear
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post #7 of 12 (permalink) Old 06-12-2013, 11:22 AM
 
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I had a Flowmaster system on my 69 and switched over to a Pypes 2.5" Street-Pro system with the "x" crossover. The droan on the Flowmaster drove me nuts.

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post #8 of 12 (permalink) Old 06-12-2013, 11:26 AM
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I bought a system off e-bay, wasn't happy with the sound so I switch the muffs over to the Dynomax and am happy. You can hear them in my burnout videos below in my sig.
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post #9 of 12 (permalink) Old 06-14-2013, 04:22 PM
 
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My car came with a 2.5" Flowmaster setup. It was fine with my low pwr 400, but now with my higher power 455, I was not happy with drone either. I welded in an H-pipe, which helped, but still a little "droney".
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post #10 of 12 (permalink) Old 06-18-2013, 12:25 PM
 
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I run 2 1/2" Pypes with crossover X pipe and Dynamax muffs behind my mildly built 455 -it has just the right sound for me, not to loud but it makes itself known when I get on it. I welded everything but the joint behind the X pipe so I could unbolt the header flange and the X pipe in case the (when) trans needs to come out
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