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#21
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On my 454 pickup I ran 3" dual with no cross over at all and had race pros on that. It was so loud everyplace that my wife simply said I had just ruined that truck, lol. I swapped for a set of street pros and the truck became so docile sounding everyplace you wouldn't think it had a nice running 454 in it.
I restored a 69 Mach 1 mustang for a customer and did a complete 2 1/2" Pypes system on it with "X" and race pros. Was a nice roller cam 351 W build. It was loud but sounded good, I think the Fords sound better with it, but it had drone right around 2,000 rpm. Ended up switching that over to street pros and they were much happier with the car. Anymore, I skip the race pros and go right for dynomax ultraflow mufflers. I've never had an application with those mufflers to date on any type of car that was excessively loud or had any drone to speak of. They are more expensive but I've been more impressed with the sound quality and control of those mufflers. On the transverse systems we are limited. Pypes sells one, and it comes with a crossflow muffler with a racepro design. The other one on the market is made by Thrush with a dynomax muffler. Something about the crossflow design however that the racepro isn't excessively loud, doesn't exhibit any drone and produces better sound quality than the dual muffler race pro setup. I run this system on 2 cars here and like it. On my wife's car she wanted it a bit more quiet. I also wanted stock appearance with factory tail pipes. So I grafted the 2" factory tail pipes into the transverse muffler. That small change completely changed the sound of the car everyplace. To the point that when cruising, inside the car, you hear the engine in front of the firewall more than the noise out the tailpipes, which makes a very comfortable car. But it will bark a bit when you stand on the throttle. I've been impressed with that change. All kinds of stuff you can do to affect sound. |
#22
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I have a similar Pypes setup with Racepros on my 67 Firebird 400 with LB manifolds. No drone at all. Love the sound.
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#23
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strange the dynomax ultra flos would be such a dramatic difference vs the race pros, they are essentially the same muffler physically, just have slightly different packing. |
#24
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I think where the Dynomax gain their sound control is with that larger 20" case muffler, they are much bigger than the Racepros.
However, I say that and run the smaller 14" dynomax ultraflows on my sons 5.0 mustang and love the mellow sound they provide. No drone, and not excessively loud like most fox bodies that run around. It has more of a mellow muscle car rumble that really doesn't grab much attention. Even removed the cats on it (it had 4 of them, lol) And generally the fastbacks tend to transmit more exhaust noise due to the fact that the rear cargo area is part of the passenger compartment (they don't have a separate trunk) yet the car is very comfortable to drive. |
#25
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i can see that, but not really apples to apples to compare a 20" case to a 14" case. i'd bet the 14" dynomax is a very similar sound to the 14" racepros.
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#26
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That's just it, the 14" dynomax case you would think would be louder but it's very docile. Extremely tame on my sons car. When I run the Racepro mufflers they are definitely much louder than a 14" dynomax.
I have a ton of idle, race, and cruise clips of different exhaust setups I've tried. When I get some time I'll post some video. But not sure what that would really accomplish since everyone has a different idea of what is loud, what is drone etc...so it's impossible to hash out the differences on a computer. |
#27
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#28
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Got the dynomax st’s Installed. All I can say is wow! I am extremely happy with the outcome. Driving it is now a pleasure with no real drone. There is some slight drone below 20 mph but totally manageable. Nothing like the drone with the RP’s. Did a couple WOT runs and I can’t tell any performance difference. The car feels so much better now that I can hear myself think while driving. Here is a quick video.
https://photos.app.goo.gl/MDN7KUc72fwDgkhA7 Thanks everyone for all the advice.
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#29
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#30
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#31
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#32
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Good luck and post up a before and after video.
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#33
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#34
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This discussion is timely, as I weigh options for my 68 firebird. I ran the 20" ultra flow in my gto with 3" mid and headers, 600hp, and was very happy. Same engine going into the 68 and plan on the 3" Pypes X.
I thought the 1st gen fbody may need a 14" case, but sounds like the 20" case should work? I was considering the complete kit from Pypes with either the Street or Race Pro- but after reading this- thinking I will stay with dynomax and the pypes mid section. I also like their Super Turbo, but sounds like it is not a true 3" muffler. Someone reported the ST input flange is 3", but internals are 2.5". Probably not a huge deal for me, but if buying 3", I want 3" ! Sent from my SM-G965U using Tapatalk
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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 |
#35
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I had a similar drone in my '69 Firebird convertible. I had the Pypes 2 1/2" system with an X, with 14" Dynomax Race Magnums. It was too loud, we could not hear each other talk while driving the car, and the drone was obnoxious.
I replaced the mufflers with 16" Dynomax ST's this fall. I love it. Still sounds like a muscle car, but no drone and I can have a conversation in the car! I bought 14's, 16's and 20's, hoping to install the largest that we could fit without major modifications.
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All of my cars are Hybrids...they burn gas and rubber! '73 Ventura, Spotts 462 roller 10.785 @ 122.79, 1.507 60 ft 2850 lbs. plus driver, 3150 race weight '69 Firebird Convertible, Spotts 455 with long branches 12.561 @ 107.62, best on old 455 4290 race weight '72 Formula 455 HO numbers matching auto, work in progress! |
#36
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#37
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That is great! Glad it worked out for you too.
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#38
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Great info & sounds like 20" is the way to go. I'm going to run my VTs till they fall off but now I know what to get. Nice car and combo sj, you ever take that car to the track?
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
#39
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No track time yet. I just got it running in early December and am working out the bugs.
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#40
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I believe the next event is scheduled for November. |
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