Flowmaster 40 interior resonance and B-quiet

[xmitsu10]

Last spring I installed a pair of Flowmaster Delta 40's and am happy with the exterior sound, but not the interior resonance at 2200 rpm. Since they are new, I'd like to keep them and was wondering how much resonance reduction I would get from installing B-Quiet Ultimate or Dynamat inside the cab (floor/doors/rear wall). Would love to hear anybody's experience with a similar situation before I break down and replace the mufflers.

Mark

[kaycee]

Where do your tailpipes exit, do you have an H or X in your pipes?

[cdowns]

where are the mufflers located// if under the cab it might help moving further back under the bed

[pat]

I have the same mufflers with dumps.

I ran almost 2 full rolls of the B-quiet ultimate or whatever name its going by today. Im not sure at exactly what RPM, I think pretty close to what you're talking about, but I experience the same resonance for a small section of the RPM range, other than that, its not too bad.

[Mondo]

I put in the "dampner" stuff first (looks like a sheet of sticky tar/aluminum). It quieted the vibration rattles I was getting with the muffler at certain RPMs. And works good inside the doors too. Then I put the Bquiet sound deadner on top of that.

It made a big difference with my 3 inch single exhaust (and engine/road noise) but I'm getting old and find the muffler still just too loud. Will try to find a quieter 3 inch or something smaller/duals later. I have this 3 inch set up on a newer truck but the catalytic converter must muffle it some too because it's much quieter.

[xmitsu10]

Originally Posted by kaycee

Where do your tailpipes exit, do you have an H or X in your pipes?

Thanks for the feedback. The pipes exit the rear under the bumper, H pipe and will be moving the mufflers from under the cab to under the bed, as they should have been located from the beginning. My dilemma is that while I am moving them, should I replace them with something with less resonance?

Mark

[keiths69swb]

I have the same mufflers with a full 3 inch system on my 72 dodge challenger. The mufflers are just before the rear end and the pipes exit just below the rear valance. I have absolutely no resonance, with nothing more than factory carpet on the floor. I honestly think it's your current placement of the mufflers not the mufflers themselves. Just my 2 cents...

[tim21391]

i agree with keith.... i have the original 40 series... i got two mufflers right beside my driveshaft underneath my bed....i have hardly any sound of the mufflers inside the cab when the windows are rolled up... roll the windows down and it sounds badass.....i think like keith said that its probably the placement of the mufflers.....i also think that if you dont like the sound of the 40 series you shouldnt of bought the 40 series you should of gotton the ones that arent as loud....thats just my opinion

[tim21391]

YouTube - 1972 Chevrolet C-10 Flowmaster 40...

that is a video of my exhaust

[Mondo]

I actually did go to the flowmaster with another chamber (50?). The muffler is under the bed (hole thru the crossmember), tip dumps near axle under truck. I think it looks cleaner without seeing a tailpipe.

Do you think it would be quieter if tailpipe exited the side or rear of truck?

[AuggieStyle]

i used fat mat in mine and it helped with the sound quiet a bit but i was going that route anyway because of the stereo system.

[stope4]

Resonance is a funny thing. I don't think sound deadner helps reduce resonance that much mainly because resonance is a type vibration caused by a certain range of sound wave. While I like the sound of the 40 series I hate the noise it creates in the cab at the RPMs you normally drive. On my first truck I put the 40's where the original mufflers go and I still had the resonance in the cab at 50 - 60 mph. I vote for getting a muffler with less resonance in the range you drive your vehicle, go stock or live with it.