Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Flowmaster FlowFX Muffler vs. Kit

Recommended Posts

I'm looking into the Flowmaster Flow FX catback system for around $500 and notice that the muffler itself is only like $50. I understand that this may not give the best results, but for $50, it's tempting to go with just the muffler for $50 vs. the $500 kit. What are the cons of just the muffler? Has anyone done just the muffler? I don't necessarily care about increased power or MPG. What I like about the Flow FX system is the lower overall sound, but still that deep throaty sound. Just enough to know something is different, but not obvious and keeps you wondering what it is.

Link to comment
Share on other sites

16 minutes ago, Therickyp said:

I did the muffler swap. It sounds great.  I don't understand why people change their whole exhaust on these trucks, just do a muffler swap and save your money for something else. 

Thanks, you did just the Flowmaster Flow FX muffler then? Happen to have a part number or link? 

Link to comment
Share on other sites

7 minutes ago, Therickyp said:


Thanks. That's the part number I was looking at, but it was showing a round, oval shape muffler. I now see there is a round or normal option.


https://realtruck.com/p/flowmaster-flowfx-mufflers/flm-71249/   "normal" shape

https://realtruck.com/p/flowmaster-flowfx-mufflers/flm-71419/   round, same part # as yours


Did yours ended up being round, bullet shaped like the amazon photo? I wonder if there is any sound difference between round and "normal"?



Link to comment
Share on other sites

I installed the FlowFX Cat Back system in my 2021 5.3. It is terribly loud. Might as well just run a straight pipe. The interior sound level is unbearable. Unless, of course, you want your truck to sound like a boat. Flowmaster Series 70 is what I have now. Now it sounds good, and not too loud.  I will starting a thread over the weekend to detail my Flowmaster FlowFX Cat Back experience.

Edited by Diamond817
Link to comment
Share on other sites

  • 3 weeks later...

I installed the FM Flow FX dual kit a month after I bought the truck. To me it isn't overly loud, especially at "Warm" idle. You can hear it going down the road and even better when you put your foot in it. I do believe that is the whole point of installing it---It sounds like a truck now!!  

  • Like 1
Link to comment
Share on other sites

I had my oval Flow FX muffler installed yesterday, 3" inlet/outlet, offset inlet/center outlet, ordered from here:




Initial thoughts on the 5 mile drive home are as follows:


It is quite a bit quieter than I expected. It has a stock/slightly higher sound level than stock with a deeper tone. When you get on it, you can tell something is there, but I can't say that someone that didn't know you put the muffler on (ie: wife/neighbor) would notice. I honestly was expecting a little more noise. It's kind of like the gentleman/dad exhaust vs. the 40 series I had on my truck in high school. Pretty much what I was going for. Just my initial thoughts and opinions may vary from others experiences here. 



  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...

Important Information

By using this site, you agree to our Terms of Use.