1969 GTO muffler experience - Pontiac GTO Forum
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post #1 of 2 (permalink) Old 04-02-2016, 10:21 AM Thread Starter
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1969 GTO muffler experience

Greetings. I just went through an exercise to replace mufflers on my 1969 GTO Judge and thought I'd share the experience considering i had some difficulty finding a muffler that I admired during this effort. My Judge is "mostly" stock, no headers, etc...Hopefully this info is helpful to others.

Full disclosure: this car is relatively new to me so i do not have the back-story on the mufflers that were on it, which model they were or how old they were.

Step 1: Existing mufflers were FlowMasters. They were quite loud, a bit of a metallic/tinny sound, some "popping" on acceleration/WOT, and significant backfiring on deceleration, which I found particularly obnoxious.

Step 2: What to replace them with?...after much research and looking for info online/sound clips I became interested by the Dynomax VT's. I liked the idea of the spring/valve concept where the idle is understated but as the throttle opened up, so did the value mechanisms for increased flow/sound. I had read some owners experienced a rattle/hum from this muffler but accepted the risk pulled the trigger anyway. Of course, I also experienced a rattle/hum that I could not bear. I presently have a warrantee claim in process with Dynomax under their 90 day sound/performance guarantee where they claim to reimburse for the mufflers, pay return shipping and add $100 to help with the labor cost to reinstall different mufflers. Note: As of this post I have not received the refund but assuming I do, I'll have no regrets with Dynomax. generally speaking the VT's were quiet but too quiet for my taste even when into the throttle.

Step 3: What to replace the VT's with the 2nd time around. Again...more research (which is very subjective as we all know). This time I landed on Borla Pro XS. At the same time I added a crossover pipe (H pipe). The Borla's are a deep tone. louder than the VT's but not obnoxiously loud like the Flowmasters. IMO...a very nice, deep muscle car sound without attracting unwanted attention and no unwanted odd noises/drone/popping/backfiring. The H pipe also seemed to even out the sound very nicely... but considering I did the H pipe & mufflers at the same time I cannot swear to which made the difference. I assume it was primarily the H and I have absolutely no regrets. If there is any performance improvement with the H pipe I believe it is minimal but it definitely sounds great/smooth. I recommend H/X pipe for any muscle car. At this time I couldn't be happier w/ the Borla pick.

I would have loved to try MagnaFlows also but was not willing to continue paying labor to try other brands out of curiosity. Borla it is for me...I hope this info is of some value to others.

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post #2 of 2 (permalink) Old 04-02-2016, 02:49 PM
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New Magflows with a crossover on my '67 when I bought it now listed for sale.

While I had the engine out for rebuilding I ordered the Gardner reproduction system with resonators, excellent fit and sound.

1967 GTO Exhaust Systems - Gardner Exhaust Systems - 1967 GTO Exhaust Sytems by Gardner
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes.

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