Flowmaster Super 40 Series Muffler Review

There are many who are considering purchasing an aftermarket muffler for their vehicle. There is so much to choose from, all with its unique benefits and sound. I bought the Flowmaster Super 40 Series muffler. Flowmaster claims it to be one of their loudest high-flow silencers. According to Flowmastermufflers.com “The Super 40 has that” deep and powerful “sound of the original 40 series but with all the performance benefits and low internal resonance of” Delta Flow technology. “I have to agree with the fact. which has a deep and powerful sound, however the inner resonance is significant. I haven’t heard the inner resonance of a delta flow, but the Super 40 Series still has quite a bit of inner resonance.

I put this muffler on a 2001 Toyota Tundra 4.7 liter V8. I ordered the muffler online and when it arrived I took it with the truck to a local muffler shop and installed it. The shop simply cut out the original muffler and installed the new one. The resonator was left alone. I also added a stainless steel tip. From day one, I have been very impressed by their sound.

Between 5 and 2 RPM the sound is very husky and deep, especially when I am actually in it, however as my RPM increases above 2.5 the cockpit sound gets a bit lower and the revs of the engine take over the exhaust pipe. In my opinion, it still sounds great, but it’s not exactly what I expected.

Performance wise, I feel like I’ve lost a bit of power on the bass. With high flow mufflers like this one, this can be common. The claimed horsepower gains are true, however the horsepower increase is found at the higher RPMs. The low-end power loss is enough for me to realize, but not enough to make a huge difference. (I’m picky)

I have not noticed an increase in MPG. I was hoping to do so, but it remained unchanged. (even with a K&N drop air filter). I keep getting between 16-18 MPG.


* Deep throaty sound in and out of the cockpit.

* Good price.

* Higher power (high RPM).


* It is not a stainless steel construction, it is painted. After several months of use, the beautiful black paint has almost completely burned out.

* Around 65 to 70 mph, there is an interior resonance that I just don’t like. It disappears at around 72 mph, so it’s not a big deal. I liked it at first, but it gets annoying after a while.

Overall, the Flowmaster Super 40 is a great product. I really like the sound of this muffler. It is deep and smooth. It is not harsh or “scratchy”. It produces a powerful sound and really lets you hear the beast that is the 4.7-liter i-force. It is one of the best Toyota aftermarket parts I have ever bought.

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