Flowmaster Flow FX questions

[Gbauer]

I put on a new Flowmaster FX axel back on Saturday. At certain RPMs it sounds like a civic with a fart box. Has anyone added a resonator to theirs and did it fix the annoying RPM ranges? Another option I'm going to try is sound deadening around the trunk area. I have a slight subwoofer vibration at high volume so I was planning on getting in there anyway to fix it.

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[Gbauer]

Update: I bought cheap Amazon sound deadening and went to town on the back end. I put a little in the tail gate under the black plastic door and then removed the floor covering, Jack and cooler. I lined most of it including the outside of the cooler (it sits in a hole in the sheet metal. There isn't a metal well there at all. That surprised me and, I suspect, that's where the noise was really coming from).

To remove the floor you flip up the tie downs, pop the plastic cover and remove the two 10mm bolts that attach it to the truck. Do that for all 4 and the floor lifts right out. To remove the cooler it's just 4 10mm bolts. Simple to do.

From there I cleaned the underside of the cooler and wrapped it as well. This stuff isn't meant for outside installation but its cheap enough to try, right?

Did it work completely? Nah but it definitely made it tolerable. We'll drive it for a couple weeks and if we (meaning my wife) still isn't happy then I'll do a resonator.

Sounds deeper inside though. No more reverberation.

Overall worth the $30. In fact I'd say it's worth the time and effort even if you don't have a loud exhaust. I might even put it under the rear seats just to deadening the interior sound even more

The real test will happen in about 10 minutes when my wife goes to drive it to her board meeting...

Amazon Basics Car Sound Deadener, 14.5″ x 10″, (10 count)Pack of 1 https://a.co/d/6hBq8Rd

Edit: wife said it made a difference. Takes the edge off the sound. Doesn't drone as much.

I think we'll still add a resonator