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Old 07-10-2019, 06:41 AM
71 T/A 71 T/A is offline
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Default Quietest 2.5" Mufflers for 69 GTO?

I have a SD Stump Puller cam with ported 62 heads and about 450hp in the 468 in my 69 GTO. Currently, I run AP Xlerator 2.5" mufflers with 14" case. I want to quiet the car a bit. These mufflers have an offset inlet and center outlet. I could go to the 18" case Xlerators. Would that be worth the swap or is there a quieter muffler with center outlet?

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Old 07-10-2019, 08:16 AM
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I ran a very similar motor with the Dynomax Super Turbo in a 14" case. Very mellow tone. If the longer case version fits it should be even quieter.

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Old 07-10-2019, 11:24 AM
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Same here, ditched the flowmasters and went with Dynomax turbos. Don't sound quite as good from outside but infinitely better from inside the car. Lost all the resonance it had before.

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Old 07-10-2019, 12:56 PM
Murphman Murphman is offline
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After 3 years the work has been completed (paint, interior, engine) with the exception of the exhaust system on my 69 GTO convertible which has been in family since ne with all matching numbers. It has the standard 350 hp with turbohydramatic with hideaways and power rear deck antenna. I am looking at exhaust systems and was leaning toward the flowmaster (17119). I have the chrome exhaust tips (2/14 inch) and would like to match the original look. You have convinced me to look at the Dynomax Super Turbo. Is that part number ST 17749? I want to have a good deep sound, but I don't want it to overpower everything. Any comments about whether I should have an X or an H pipe? Many thanks.

Murphman

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Old 07-10-2019, 05:08 PM
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I have the 17749 Super Turbos on my '64 GTO convertible - they are a 2.5" inlet/outlet muffler. I have an X pipe and the exhaust is 2.5" all the way including the 2.5" RARE RA exhaust manifolds.

Selected these mufflers so that I didn't drive myself crazy with the top down (which it is 95% of the time).

I'm very happy with the results.
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Old 07-10-2019, 06:28 PM
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Recently switched out 14" Race Pros for 21" Dynomax STs. The car is so much more enjoyable to cruise in now, especially on drives longer than 10-15 minutes.

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Old 07-10-2019, 11:29 PM
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I would not ever consider super turbos quiet at all.Tom

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Old 07-11-2019, 09:12 AM
71 T/A 71 T/A is offline
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I had Dynomax Super Turbos on a 72 Formula and they droned big time at 2000-2200 rpms. Installed Goerlich Xlerators and drone is gone. No way would I used those mufflers again. Terrible drone.

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Old 07-11-2019, 09:34 AM
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"You have convinced me to look at the Dynomax Super Turbo. Is that part number ST 17749? I want to have a good deep sound, but I don't want it to overpower everything. Any comments about whether I should have an X or an H pipe? Many thanks"

From what you have said, I am sure you will like the super Turbo, especially the longer case version. I have run the ST on 3 different engine combos, and was never disappointed.

Regarding X or H... I have used both on my current engine, but it is not an entirely an apple's to apples comparison. With the X I was running the long case ultraflow, and with the H am running the short case ultraflow. As expected the short case is louder, but the H tends to create more of a deeper rumble as compared to more of a "whine" with the X. Think NASCAR'ish sound with the X. In hindsight, I would have used the X in my new combo due to the louder short case ultra flows.

Many here have way more experience in this area than I do, but that was just my experience from a limited field of test cases!

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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 07-11-2019, 10:00 AM
Murphman Murphman is offline
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Great information. Many thanks. I will look into the Dynomax Super Turbos 17749 with a possible X pipe and the 1969 chrome exhaust tips which I have. Does anyone know exactly the location for the exhaust tips in relation to the bumper jack insert? How far should the tips protrude from the bumper? From the pictures I have seen it is difficult to tell especially when the exhaust systems differ. I want to keep the original look as closely as possible.

Regards,

Murphman

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Old 07-12-2019, 09:03 PM
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Here's a pic of the tips from 1969 Accessories brochure-
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Old 07-13-2019, 08:06 AM
Murphman Murphman is offline
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Thanks for the pic. New exhaust sytem will be installed next week.

Murphman

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Old 08-27-2019, 12:22 AM
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hi

how are you?

I have run this muffler for 40 years on my 400 pontiac with hooker super comp headers..2.5" in and 2.5" out:

https://www.amazon.ca/dp/B00029J3C0/...v_ov_lig_dp_it

I can tell you, all my friends have the flowmaster 40 .....line of flowmaster 40's....some have flowmaster 44, some have flowmaster 40 series.... Their 40 line is quite the naming convention.

i have looked into it extensively....dynomax vs flow master.

So the super turbo above is considered the quiet end of dyno max... Ummm i would say no...... my gto sounds just like if not as close to the flow master 40's.... it is mean... the dyno max super turbo's are about $30 less per muffler .... I have never had a drone problem... And I have 390 gears...........run 3000 rpm just to get speed limit on highway......... however choose them for my car when it was built, was a good choice...

it's good for up to 350 hp - 400 hp... so that pretty well covers most builds.. if you call dyno max and say i want one better muffler, their next muffler up is ultra flo 17219.. again offset on one side and center on other, both 2.5"

only $30 each more... So.... step up one or buy flowmaster.....
again dual exhaust setup... pm if you want sound videos from my car.

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Old 08-27-2019, 12:29 AM
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Quote:
Originally Posted by The Champ View Post
I have the 17749 Super Turbos on my '64 GTO convertible - they are a 2.5" inlet/outlet muffler. I have an X pipe and the exhaust is 2.5" all the way including the 2.5" RARE RA exhaust manifolds.

Selected these mufflers so that I didn't drive myself crazy with the top down (which it is 95% of the time).

I'm very happy with the results.
Exactly my setup but in a 71 - nice low growl.

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Old 08-30-2019, 09:57 AM
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I also use and like the 17749 mufflers..

I am going to try a pair of #17197 Walker Truck mufflers without tail pipes.. They are pretty big and have perforated tubes which should flow decently. This is for a 69 el Camino with a 390 horse Impala 427..
https://www.walkerexhaust.com/produc...on_search.html
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Last edited by 389; 08-30-2019 at 10:14 AM.
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Old 08-30-2019, 02:50 PM
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Nice deal direct from Holley on the 17733 on eBay. $24.99 incl shipping.

https://www.ebay.com/itm/Dynomax-Sup...t/351009474955

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Old 10-14-2019, 02:52 AM
android 211 android 211 is offline
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I have the long case Dynomax mufflers on my automatic 69 GTO convertible. I used the Pypes 2 1/2" headpipes with stock logs and Waldron 2 1/4" tailpipes with resonators. It also has a H pipe. The car is very quiet at all speeds.
The Dynomax is one of the highest HP mufflers despite the very low db readings.

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Old 10-22-2019, 12:10 PM
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Dynomax Super Turbo 17749's here also with a Flowmaster 2.5" mandrel bent pipe kit and an H crossover. No resonance at any speed or rpm. Many years ago....just prior to installing the Dynomax....I ran a set of Flowmaster 50 series mufflers. OMG. Impossible to hold a conversation due to the interior resonance with those mufflers.

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Old 10-22-2019, 07:31 PM
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Quote:
Originally Posted by android 211 View Post
I have the long case Dynomax mufflers on my automatic 69 GTO convertible. I used the Pypes 2 1/2" headpipes with stock logs and Waldron 2 1/4" tailpipes with resonators. It also has a H pipe. The car is very quiet at all speeds.
The Dynomax is one of the highest HP mufflers despite the very low db readings.
What kind of resonators are you using?

Thanks

Greg

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Old 10-23-2019, 09:15 AM
71 T/A 71 T/A is offline
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I just got the Dynomax 17748 mufflers on my 69 GTO and they are much quieter than the AP Exhaust Xlerators I had and no drone!

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