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Flowmaster Exhaust Systems - 817423

Cat Back Exhaust - American Thunder Series
  • $748.95
  • Free Shipping
  • Ships Between 1/24 - 1/28
  • What Do You Drive?


  • Style:
    Dual Rear or Side Exit (409 Stainless)
  • Material:
    With Dual Exhaust Tips
  • Part #:
  • Main piping diameter: 2.5"
  • 50 Series HD Muffler
  • Includes dual 3" exhaust tips
  • Includes exit pipes for dual rear or dual side exit
  • Download installation instructions (PDF)

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Flowmaster Exhaust Systems Part #817423 Customer Reviews

Average Rating

15 Customer Reviews

Dollar for Dollar, You can't Beat the Performance

Reviewed by John M H (SUFFOLK, VA) Reviewed for a 2008 Dodge Ram — Jan 10, 2018 7:29 AM

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I had a shop install the Cat Back American Thunder system on my RAM, 5.7 Hemi. This was a "replacement" for a system that came with the truck when purchased used. My son and I can not get over the marked difference in sound and performance with this new system. It is like driving a new truck. The engine runs smoother and operates like it has another 40 horses under the hood! At idle, the sound is barely noticeable in the cabin. Acceleration is the sound of new power. Great purchase!!!

Nice system overall

Reviewed by Kris N (Snohomish, WA) Reviewed for a 2008 Dodge Ram — Dec 08, 2017 8:18 PM

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Always love Flowmasters and have had them on our family's trucks for years. Flowmaster sales and customer support folks are absolutely the best! Really nice system and pretty dang easy to install with simple tools. Make sure you have a breaker back and a deep 15mm socket for the install. Feedback: The exhaust tips wouldn't tighten enough, so have to tack them probably. Clamps have to be adjusted to the right position or you have small exhaust leaks which is slightly tedious.


Reviewed by Konrad S (Kewaunee, WI) Reviewed for a 2008 Dodge Ram — Mar 07, 2017 7:10 AM

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Had to get rid of the stock exhaust. Always was a fan of Flowmaster. Installed it and noticed a 1+ mpg increase as long as I keep my foot out of it. Nice sound, not too loud that every cop will hear me but loud enough to be noticed.

2008 Ram 1500 Big Horn w/ American Thunder Cat Back

Reviewed by David M (Nashua, NH) Reviewed for a 2008 Dodge Ram — Jan 03, 2017 6:06 AM

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The system looks and sounds very good. Two changes I would like to see is that the: Muffler in the Stainless Kit should be made of Stainless also, And the 3" tube should go all the way up to the Cat/Headers. I purchased a 5 ft length of 3" SS tubing for $45 on ebay to do this. This only needed to be swagged to 3" ID by a local Muffler Shop.

Went in easy and works great!

Reviewed by Chad D (Des Moines, WA) — Sep 12, 2015 9:34 PM

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Took me and a buddy just over an hour to do the job once the truck was raised. All the clamps worked great. Seemed a little close to the spare till we wiggled and twisted everything al little tighter. Just don't clamp everything all the way down till it is all hanging and right where you want it. My only complaint is that my chrome tips turned golden after taking a trailer up a few mountain passes. performed great though. I just have golden pipes out the back now.

Mopar sound!

Reviewed by Steven Y (Tully, NY) — Apr 25, 2015 10:12 PM

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This is a real nice kit! Well thought out and constructed! Everything sounds awesome, a little louder than stock.I put it on my Hemi QuadCab. Nothing sounds nicer than that Mopar sound!

Great Exhaust

Reviewed by Christopher R (Sneads Ferry, NC) Reviewed for a 2008 Dodge Ram — Nov 19, 2013 3:18 AM

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1 of 1 people found the following review helpful.

Bought this Cat-Back kit form my 2008 Dodge Ram 1500. Had the old one off and the new one on in about an hour and a half, and it only took that long because the band clamp bolts on the original one where stuck on there good. This kit fits perfect, no modding required. Gives a deep rumble sound which is what I wanted. Could be a bit cheaper for what it is but its one of the cheaper ones already that's Stainless. Make sure you give about a 1" weld on all pieces to prevent them from vibrating off.

Nice exhaust for the right price

Reviewed by Daniel S (EL MIRAGE, AZ) Reviewed for a 2008 Dodge Ram — May 14, 2013 6:18 AM

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0 of 1 people found the following review helpful.

Exhaust is a great value. Gives a nice rumble. There is some noise in the cab, but I like it. Not as aggressive sounding as I had hoped, but I'm sure after I get a tuner and my CAI I'll be very happy. Overall a nice exhaust!

Flowmaster American Thunder Stainless Steel exhaust system.

Reviewed by Thomas B (Oak Lawn, IL) — Apr 04, 2013 9:13 PM

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1 of 1 people found the following review helpful.

I looks as good as it sounds, and was very easy to install. The other thing is that I am still able to use my existing spare tire.

2007 dodge ram 1500 crew cab, not loud in cab

Reviewed by Brendan S (Rocky Point, NY) Reviewed for a 2007 Dodge Ram — Dec 13, 2012 7:02 AM

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2 of 2 people found the following review helpful.

Nice exhaust, took about 2.5 hours to slap up with hand tools. Nice clean install not to fond of the clamps, i like the other u clamp style that really crimps on the pipe but not a big deal. With out a doubt getting more push out of my hemi and also having that great deep clean sounding mopar purr. Haven't noticed anything with gas really still in the range of 13 to 13.6 mpgs. Think it went down a point or two only because I keep hitting the gas to here it more. Very very happy with it so far.