nice mellow, but beefy sound.

none

z

Deep mellow tone, not too loud. Makes truck sound powerful.

Nothing really so far, except for some minor adjustments to the truck while putting it on. As far as sound, it's perfect.

I just got my permit, and me and my older brother who is unable to drive, wanted our truck to be louder. This muffler is exactly what kind of sound I wanted.It doesnt crackle when you step on the gas. The tone is a very deep, and mellow tone.The interior noise is hardly noticeable, which is good.

Good deep sound, very minimal drone

Price is high for muffler only

After purchasing an entire magnaflow cat-back system with the T304 stainless stell pipes, I relaized the muffler was nothing more than an over priced glasspack. The interior resonance (drone) was ridiculous between 1350-1700 RPM, espeicially if the tranny dropped into OD.
Did some research, spoke with Flowmaster Tech support for nearly 30 minutes. After some additional reviews, I decided to purchase. Couldn't be happier with the deep sound, low cab noise, and feel of breathaibility in the exhaust system. If your looking for something on an SUV or truck to get some additional sound and HP- look no further. A couple friends have sworn against flowmaster until they heard this one.

Great mellow sound at idle, but growls pretty good when you accelerate. Nice improvement in horsepower at cruising and passing speeds.

Not an easy install to the original tailpipe, had to go have an internal sleeve built to make it fit.

Great sound, not overbearing at all in the cab, which is good since this vehicle is used primarily for towing. Definite improvement in h.p. from 2-3k rpm's.

Excellent quality product. Good welds, heavy. Nice sound outside the truck.

Lots of in-cab resonance at 1800-2000 RPM. Very annoying.

Good quality muffler with a nice performance sound. Loud inside the cab. No change in performance or mileage over the OEM muffler.

Similar Products Used:

Flowtech Afterburner, Cherry Bomb, OEM.

deep rich sound

none

I had the 40 series installed and now with help of my new hearing aid I can tell the 70 series is by far my new choice for the 6.0L vortech. It gives that deep low tone at idle, and almost no in cab noise.

Similar Products Used:

40 series flowmaster

Great Price on Ebay $99.00 with shipping

Drones somewhat. Inside resonance not a plus.

This muffler is not loud but drones a little bit in my 2003 GMC envoy 4.2. There was a definite increase in my low end torque and the car takes off quicker. Along with the muffler I have an intake and OEM piping with a bullet performance tip and no back resonator. Many mufflers shops told me that any aftermarket muffler would drone inside due to the fact that GMC's 4.2 engine for envoy is a High Output engine. I had been reading and investigating for a long time on the quietest muffler I could possibly have on my envoy. So I ended up with flowmaster 70 series. The wife thinks it’s a little loud for her. To me all flowmasters are loud. I kind of got use to it. It really gives that deep grumble sound upon acceleration. When cruising its hardly noticeable. If you want quiet keep your OEM muffler.If you want performance be ready to sacrifice sound. At least on the Envoys.If I you don't care about sound or drone get a straight through muffler.

Similar Products Used:

Bullet Performance Muffler

Great sound, noticeable power increase.

Not as loud as I was expecting, but the tone is still there. Trust me youll like it!

The 70 series American Thunder Exhaust System is actually more than I thought it would be. Besides an awesome sound, the performance gains are pretty satisfying. I noticed a small gain in torque and a definate increase in acceleration and passing power. When they say horserpower gains between 15-20 they arent kidding. I recommend this exhaust to all Silverado drivers.

Great Flowmaster sound, minimal interior resonance, more power.

None yet.

Removed the Magnaflow Universal muffler and had the Flowmaster 70 series muffler installed. WOW!! What a difference! Gone is the "drone" and interior resonance that I had with the Magnaflow. It was especially bad when climbing a certain hill near my place. Did the same hill with the Flowmaster, and experienced very minimal interior resonance and drone. It certainly does what the manufacturer says. Still has a great exhaust tone. Love the Flowmaster sound. Growls on acceleration and quiets down while cruising. Still has that wonderful "choppy" sound at idle. Also noticed a definite improvement in power and acceleration. Has passed all MY tests with flying colors. The FINAL test will be when I tow my camper (the interior resonance was bad, when towing with the Magnaflow). I wanted a performance muffler that I/others could hear :-) but without the annoying interior resonance....and Flowmaster has certainly delivered with the 70 series.

Similar Products Used:

Magnaflow....great sound, but way too much interiore resonance for me.

Noticeable high end torque increase while towing race trailer Mellow tone, no drone ever and it's just the right loudness. It's there but not ear deadening Mileage increase noticed after intake and chip Just overall great sound

The fact that I went the cheap way w/ a single outlet system :(

I drive this beast daily, and I didn't want a horrible drone sound or anything of the sort. I'm very picky when it comes to exhaust, and I figured I'd give the 70 series a shot for this truck. WOW! It really makes that 454 come to life! When I fire it up, it's got this mean as hell sound, idle it's almost like stock. Acceleration, it's got this aggressive, smooth, mellow tone (sounds best under acceleration between 2-3 thousand rpm's). I can't stop mashing the gas. I was concerned when I was looking on Flowmaster's website that it would be fairly quieter than I anticipated, but after it broke in more and more, the true sound came to life. It's just god awesome. People tell me that they have 40 series or 30 seres on their pickups, and I just laugh, because I know their trucks don't have that same quality sound that mine has. Everyone that rides in my truck asks me if I am running Flowmasters, and when I tell them yes they can't believe what they're hearing because they think that all Flowmasters are terribly loud. Overall, this is a great product! I'm due to replacing the exhaust this summer for a dual out system with possibly a Spin Tech setup, the only thing holding me back is the fact that my truck already sounds so damn good!

Similar Products Used:

Magnaflow 14" on dodge, not loud at all really Borla on 5.3 gm, awesome sound My own muffler hehe