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Not Diggin' My Ultra Flow Mufflers

6K views 20 replies 13 participants last post by  lotsacars 
#1 ·
So I installed some Dynomax Ultra Flow Mufflers and there are several things I don't like about them. Hoping to pick y'all's brains to see what my next steps should be.

System Details
- 995 Caprice Wagon. Stock Engine, T56 car (which matters on downshifting per below)
- Factory Manifolds
- Factory Test Pipes (no cats)
- Dynomax 2.5" intermediate Pipes
- Ultra Flow Stainless Direct-fit Mufflers (2.5" in and out, offset)
- Stock Wagon Tail Pipes (2")
- Stock Wagon Resonators in place

The stock tail pipes go into the muffler with a custom adaptor. I made a slip joint with a 2.5" OD, 2"ID split sleeve (304 stainless). The leading edge of the adaptor has a 45 degree chamfer to keep the exhaust gasses from hitting a brick wall. I'm not too concerned about flow, but I eventually want to at least get over the axle with 2.5" pipe. For now I'd like to stick with what I have per above.

What I Don't Like About The Sound
- Too loud at anything over 1/3 throttle
- Inconsistent loudness: It sounds great idling around the driveway and taking off moderately, but goes to ignorant loudness levels without much throttle input.
- The bimodal sound reminds me of a ricer
- I get lots of popping when I downshift (T56 car). Even some loud pops. Sounds kinda silly.

What should I do next?
- I know I need cats. The T56 has delayed their install. Will that make it much quieter? I don't drive the car much, but I know this is the right thing to do. I'm hoping it quiets it down.
- Will an X pipe really help? I am pretty low in this car, and I use a 4" custom driveshaft. It's tight under there. I had hoped to not put in an X-pipe but would consider the Pypes kit. Making a custom crossover is outside of my fabbing skills.
- Should I select a different muffler? This was the only performance off-the-shelf muffler I saw. Maybe try some from other manufacturers? I know the 17749 is popular. I had avoided it due to my lame fabbing skills. Maybe I'll find a way to make this happen.

Any other suggestions? I could use some help getting this dialed in. I'm considering this install a failure at this point. :mad:
 
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#2 ·
I'm not too sure why you would buy a "performance ultra-flow" muffler when you're not concerned about flow.
You are concerned about having a quiet engine.
I am too as my car came with duals and thrush mufflers, no resonators.
It rumbles at idle and gets downright nasty when you romp on it.
So I too am interested in what suggestions might come up here.
 
#3 ·
Why avoid the 17749? Love mine. Is it cause it doesn't have the hangers? If so, get the hanger and frame bracket for a 91. They finally make both now. Bracket screws to frame. Holes might even be there. Then other piece slips into it and is held to muffler with rear clamp.

Unless a wagon is that different?
 
#5 ·
Why avoid the 17749? Love mine. Is it cause it doesn't have the hangers? If so, get the hanger and frame bracket for a 91. They finally make both now. Bracket screws to frame. Holes might even be there. Then other piece slips into it and is held to muffler with rear clamp.

Unless a wagon is that different?
Yes, it is my inability to make brackets. This '91 hanger idea is new. I'll check it out - thanks!
 
#4 · (Edited)
Yes, an 'X' pipe will help quiet things down. That's because when any single exhaust pulse reaches the 'x', it has twice as much pipe to expand and split into.
Lot's of good exhaust info here: http://www.grail-ss.com/GRAIL Website Files/ExhaustScience.pdf

A number of us (myself included) have gone the route of the Pypes X-pipe and Dynomax VT's (all stainless 'mufflers', with an internal, spring-loaded 'flap' that opens under 'higher exhaust pressure' (generally a result of movement of the right ankle). I'm currently running the CIA Tri-Y's, thru the CIA 570CFM CAT's, Pypes X-pipe, Dynomax VT's & dumped. Could not be happier. The car has a nice rumble at idle, no drone, no head-ache inducing 'noise' while cruising, and lets you know when I'm applying a bit more power };^)>. One other nice thing is that the wife will now ride in the car with me (not so with the prior arrangement). I did add a welded in O2 bung right at the X, so I have a place to put a wide-ban sensor for tuning the car.

I'm running a 3" driveshaft with good clearance (not in the pic, the OEM shaft got replaced when I went to the 3.90 spooled rear end), so I don't think a 4" would be an issue.

For yet another 'crappy cell phone exhaust vid (not my car): https://www.youtube.com/watch?v=LMGAkRkShF8

Pic of my current set up:


Pic's of my prior set up (2 1/2" pipe, Flo-Pro V-Force single-baffle, empty 'cans' (http://www.flopro.com/vforce.html), each with 6 feet of straight pipe, straight out under the rear axle... 'LOUD'):





HTH.

.
 
#7 ·
#8 ·
Dunno about the X-pipe helping with 'popping' on down-shift deceleration. Even with a 'built & guaranteed' 4L60E, I try to avoid that behavior.

With the prior (OEM) 4L60E tranny (which I was trying to break - by downshifting it - so I'd have an excuse for putting the new motor & tranny in!), my prior 'straight-pipe' set up would 'cackle' like a crazed witch. But I never had an x-pipe in front of that set up.

So... what's so wrong/bad/undesirable about exhaust cackle on downshift?
(some folks LIKE that sound!)
 
#9 ·
91ss: you have a picture or sketch of how that works? I saw the two walker parts but not sure where they go. I am about to put the 17748s on my ride, instead of the 17749s because then I can use CIAs 2.5" S-S over-axel pipes and resonators, which are bent to fit a center outlet muffler. This is my first exhaust install, so I don't really know what I'm doing.
 
#11 ·
I'll see if I have any pics showing or will try to take some. Did you see the actual pictures of the parts? Rockauto shows pics. 35270, called hanger, is the piece that bolts to the frame. Lays flat and goes left to right wise. Then 35662, called bracket slips into the center rubber piece of the hanger. It hangs down with flat part with holes to meet up with muffler clamp. The muffler clamp has the tips of the U point up to go through that bracket and then nuts go on. One caveat, the 91's factory set up uses a 2 1/2" clamp back there. So might have to file the holes for something smaller.
Try this sketch.
 

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#10 ·
So I installed some Dynomax Ultra Flow Mufflers and there are several things I don't like about them......... What I Don't Like About The Sound
- Too loud at anything over 1/3 throttle
- Inconsistent loudness: It sounds great idling around the driveway and taking off moderately, but goes to ignorant loudness levels without much throttle input.
- The bimodal sound reminds me of a ricer
- I get lots of popping when I downshift (T56 car). Even some loud pops. Sounds kinda silly.......
It's almost unheard of for someone to complain that the Ultra-Flows are too loud. In fact, you're only the 2nd person I know of to make this complaint, and I've been around for awhile.

Cats and X-pipe will 'soothe' the loudness a bit, but I just can't see you buying another muffler aside from maybe the DynoMax VTs and OEM from a dealer, that would be quieter.

As for the popping on deceleration.....that's not a muffler issue, that's a fueling/programming issue. My 2014 SS (like most LSx engine cars) does that all the time. LOL cwm2 ....turns a lot of heads!

KW
 
#13 ·
I have a similar set up and would NOT classify it as loud. Not even close. It's stock-quiet while cruising. Mine is cammed with a T56, stock manifolds and cats to UltraFlow cat back. I would attribute your loudness to not having cats. They do make a difference in both volume and tone. Get those puppies back in there and I think you'll be pleasantly surprised.
 
#15 ·
Put the cats on, an x or h pipe will stop the popping, leave resonators or use dynomax bullet resonators like I did. You can't tell what you like until you get the cats on and either an x or h-pipe. I have been running Dynomax ultraflo SS system for 10 years and still like the sound of it.
 
#16 ·
......I have been running Dynomax ultraflo SS system for 10 years and still like the sound of it.
Ditto....except for about 14 years.....

KW
 
#17 · (Edited)
I took the Dynomax Ultraflows off my 94 the first week I had the car because I hated the sound. They are very loose and sloppy sounding, this was with borla shorties and cats. I replied them with $20 summit turbos that sounded a WHOLE lot better IMO. It is a very subjective topic!

I mean hell, my favorite sounding muff is Flowmaster but somehow a whole bunch of people hate those (mainly because of misinformation that gets perpetuated by the 'net regarding their performance, but a lot of people say it makes your car sound like a mustang....which is impossible...an LT1 will NEVER sound like a 5.0 or 4.6).

Anyway, if you are looking for a more consistent, tamer sound at idle/part throttle and a nice roar at WOT, a turbo style glass packed muffler will likely fit the bill. They will be quieter overall and tighter sounding. Drawback is that you won't get that powerful of an idle sound with them, they may rob you of a tiny bit of HP over a more free flowing straight through style like a Dynomax (though in all honesty, this won't be noticeable and probably worth it if you like the sound) and most turbo style muffs won't last forever due to the design. When I swapped the turbos onto my SS, I also swapped the bola headers out for flow tech afterburners, deleted the cats and welded up a 2.5" system out of scrap pipe. It sounded great. It wasn't the loudest car, my 96 with no headers, cats and Flowmaster American Thunder exhaust was louder all around, but it had a very nice, powerful sound without really any drone at all and no inconsistent loud points in the power band.


Your other option would be to tame the existing setup by using cats and an X pipe which will all help to soothe the sound as KW and others have already mentioned mentioned.

Exhaust is a very subjective thing. My personal opinion is that HP variations are so slight between different mufflers (comparing like-model muffs at least, not straight through race bullets to restrictive/quiet 50 series flow master) that you shouldn't worry about that too much unless you are trying to get every tenth out of a race car. Any performance muff will be a huge improvement over stock and a well designed exhaust system as in correct exhaust pipe and header primary/collector sizing, will do much more to make power. Just go with what you like the sound of.
 
#18 ·
- I get lots of popping when I downshift (T56 car). Even some loud pops. Sounds kinda silly.
LOTS of good advice already posted.

I can virtually guarantee that the X pipe will ELIMINATE the popping 100%. LT1's are known for this, especially on B bodies with true duals. The stock exhaust masks it well, but even then, it can still be heard.

I am thinking that resonators, and an X pipe will go a LONG way towards quieting it down to a level you'll like. Plus, the X pipe helps with keeping the low-end torque where you want it.
 
#20 ·
.....I can virtually guarantee that the X pipe will ELIMINATE the popping 100%. LT1's are known for this, especially on B bodies with true duals. The stock exhaust masks it well, but even then, it can still be heard.......
I've never had popping from the exhaust on any of the four B-bodies I've owned. And only one had a X-pipe.

What's supposed to be causing this in all these 'other' cars?

KW
 
#21 ·
...I know I need cats. The T56 has delayed their install. Will that make it much quieter? I don't drive the car much, but I know this is the right thing to do. I'm hoping it quiets it down...
Was this because the factory cats didn't fit? It's tight, and may require a small modification, but they do fit. Some have had the factory cats rotated in the factory pipe (cut, rotate, reweld). I was able to shave a tiny amount off of my slave adapter and now everything's coexisting. It's very tight (like thickness-of-two-business-cards tight!) but they fit and there's been no issues in the six years it's been that way.

To expand on what I said above, get the cats back on and your loud popping should go away. I currently have no interior (just two seats and a headliner) and other than obvious road noise at speed mine is quiet. And I downshift. Alot. Because T56 :D
 
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