View Full Version : fluttering/flapping noise out exhaust

02-26-2011, 11:21 PM
i have had this stupid fluttering noise coming out my exhuast since i got it redone its stock mani. true dual to 2 flowmaster 40s no cats and when you rev it up as its coming down it makes this fluttering noise like a piece of paper next to a fan and its driving me nuts does anyone else have this issue BTW its on a 96 350 vortec if you know what im talkin about and have fixed it please let me know!! also i have a random misfire and it also ticks out of the muffler at idle kinda weird.

02-27-2011, 12:27 AM
I think the fluttering you're hearing is normal. I dont know the source or specific name for the problem, but I experienced the same thing when I had the same exact setup on my 95 F150 351W.

02-27-2011, 12:48 AM
its pretty annoying if its just normal anyone else have some input

02-27-2011, 09:23 AM
It's possible you got one or two defective mufflers, a baffle may have broken off idea and is rattling and you notice it when it's at idle and coming down because it's quieter. If I were you i'd email or give Flowmaster a call and see what they say about it.

02-27-2011, 12:58 PM
back when i had true duals with flowmasters and tailpipes clear out the back i had the same noise. Its normal but it is kind of annoying. (if its the same sound your talking about) x pipe may fix it.

02-27-2011, 01:01 PM
Do you have tailpipes or is your exhaust dumped?

02-27-2011, 01:06 PM
now that i think about it, it had the same noise with no tailpipes too (i had flanges i could unbolt the tails.

Just flowmasters, and no equalizer setup causing it.

02-27-2011, 02:27 PM
ya it is just dumped im gonna put a x pipe on it so and hopefully that can solve this crappy noise.

02-27-2011, 02:47 PM
yeah cause if you notice if you put your hand over the tailpipe the pulses coming out are pretty violent, and mixing both banks together may make the flow smooth enough to get rid of it.

02-27-2011, 05:26 PM
thats what im hoping for idk i found a x-pipe on ebay for $30 sounds like a deal to me

02-27-2011, 06:13 PM
What you are experiencing is par for the course for Flowmasters, especially if you don't have cats.

Lesson learned: Don't buy Blowmaster crap anymore.

02-27-2011, 07:38 PM
ya i am gonna get some hooker aero chambers for my next exhaust

02-28-2011, 07:02 AM
ya i am gonna get some hooker aero chambers for my next exhaust

Excellent choice. I don't have first-hand experience with that muffler but there are several reputable and honest folks here who use them and having nothing but praise for them.

03-03-2011, 08:16 AM
I now have a 97 chevy silverado ec... And i have the same problem with that fluttering noise i had true dual flowmaster super 40's, with the cats and i was hearing that noise so i took them off and put on brand new flowmaster 10 series one chamber no cats and the noise is still there although i have no crossover ( h or x pipe) i just gave up on finding the source people still say it sounds good

03-03-2011, 09:25 AM
Seems that the common denominator here is Flowmaster mufflers and divorced duals, no crossover. Get an H-pipe put in and see if that solves it, if anything it'll smooth out the sound and add some power.

03-05-2011, 11:24 AM
True duals with no crossover, x, etc...will flutter, just the way it is.

907 Chevy
03-05-2011, 12:37 PM
It could also be an exhaust leak.When you start your truck pop the hood and look for a leak especially around the mani-y pipe flange area.Or run your hand around those areas before they start getting hot.You'll be able to feel the exhaust coming out if there is a leak.

03-05-2011, 10:01 PM
Could be a leak, but if you hear the flutter at the tailpipe after the truck is warm, just the way it is. Trust me, you don't hear it when driving, this is what makes true duals louder than single in/dual out or a true dual with a x, raspy.

03-06-2011, 01:21 AM
I've got a flutter on my drivers side exit. Only noticeable at idle. It didn't do it until I welded on the exhaust tips. It has to do with the dynamics of the pipes as they meet the atmosphere, I presume.

03-06-2011, 07:47 PM

here is a link to what the "Flutter" noise i am talking about is this is not my truck but its basically the same setup just different mufflers listen when it comes down off the rpms i figured i would post this so i can make sure you guys are talking about the same noise as me.

03-10-2011, 05:37 PM
bump anyone know have any input?

03-10-2011, 05:49 PM
x-pipe & spintechs

03-10-2011, 06:49 PM
x-pipe & spintechs

It took me a while to turn on to spintechs, and the are still a bit raspy for my taste. But they can sound amazing.... 3" pipe, X-pipe and Spintechs IMO. Somehow Spintechs can make a cam sound bigger, must be the higher pitch tones. I've considered spintechs on my next build, but now I'll stick to my flowmaster Super 40's on my silverado

Vids of cars I've made of spintechs that where in my shop


03-10-2011, 08:35 PM
yeah on lsx engines they get REAL raspy (i love it) with no cats. Gen one motors arent too bad tho. as you could see in the vid above.