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Any Concerns about Flowmaster American Thunder

954 views 13 replies 10 participants last post by  drive_55_not 
#1 ·
I have an opportunity to replace my stock axle back system with Flowmaster American Thunder (the ones shaped like a rectangle box) from someone who put 3K on them in convertible and found them to loud for that car. I listened to all the sound clips I can find, and they sound good to me. Need to make committment by phone and pick them up. Any concerns you can think of? Thanks.
 
#4 ·
I love mine! Then again, I also love that old school Flowmaster sound - as cwhit23 mentioned, some don't.

I don't think they are too loud, but they are really deep, especially below 2,000 rpm, so they can be heard from a ways away. It will turn some heads, but I really don't think they are loud enough to get pulled over for.

As for drone (probably your chief concern), I can only speak from my experience when I say that it is absolutely not an issue for me. The car is a manual with 3.73s, and a 65 mph freeway cruise has me over 2,000 rpm. Even around 2,000, I really don't hear it much. The only rpm range where I think it "drones", is 1,500 - 1,800, and then only under light acceleration in 4th or 5th gear. Btw, the rest of my exhaust is stock. If you have an auto and 3.31s, it may be a different story for you - I can't say for sure.

Hope this helps!
 
#5 ·
Flowmaster sound is great. But check the finish...I've read about the black finish flaking/chipping off (wish I could find the site for you).
 
#6 ·
^^^^^ if he is talking about the exhaust I think he is speaking of it is the model above those which are completely rectangle now rounded rectangle. There is thunders and thunder classics. I know he stated thunders but, his description sounds like the classics.
 
#10 ·
I do - I Think they sound great. Very deep rumble at idle and lower rpm. Very nice rumble/burble on deceleration as well. They sound pretty aggressive without being obnoxious. I drove to my dad's house after I installed them (he's a Chevy guy) and he commented, "Boy, Ford sure does make some good-sounding V8s."
 
#9 ·
I have Flowmasters myself. Personally I am thinking of getting rid of them and getting a set of SLPs just because my Flowmasters have developed a rattle. But I do love their sound.
 
#11 ·
I personally have what you're looking at. They are louder than stock, but not by a ton. They have a bit cleaner sound/less raspy than stock, and are definitely deeper. There's a slight drone around the 2k rpm mark, but it's not bad at all.
 
#12 ·
If they're black, then they're the Super 44 muffler. Flowmaster has been phasing out using the original 40 in their American Thunder kits for all model years. So they won't have much drone on the inside of the car but a healthy sound to those you go by.
 
#13 ·
I cross-referenced the part number stamped on my mufflers with Flowmaster's catalog, and they are 40 Series Delta Flows.

Part number is 842543. Note that this is the part number for the individual muffler, not the entire axleback kit, which is 817460.
 
#14 ·
I ran the square SS Flowmaster 17460 axleback's on my 2010 GT for a year,, I have the 3.31 rear and in the 1500-2000rpm highway cruising range they droned badly ... Especially when under load climbing a hill.

But, I put up with the drone cause they do have a nice deep growl to em' .. And they are rather loud WFO ...

After I installed a Roush TVS the cabin vibrations became a mind-numbing bone shaking constant drone .. I had a pair of Thrush resonators installed and that reduced the drone but was still worse than before the blower ...

I removed the Flow's and installed the MAC boom-tubes with the resonators and they sound pretty close (a little quieter) to the flowmasters with zero drone ... :)




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