I just got my 2004 V6 sport 4runner and joined this forum, so I figured I should contribute something useful. Today I got a gem installed and I wanted to share.
Flowmaster 50 SUV series muffler review...
First off this is the muffler The Flowmaster Super 50 Series (SUV) Muffler Mufflers&sc2=Super 50 Series SUV&sc3=&sc4=

For a sound clip click on the link and then hit ( Click here to play video )
The engine note in the video if different, but the sound level is about the same and gives you an idea of what your getting into.

To start, sound is a very subjective topic and to make matters more complicated, I noticed that when reading reviews about flowmasters on this forum people were always referring to a Flowmaster 50. This would be OK but the problem in that Flowmaster make the 50 HD series, the 50 series big block and then the Super 50 (SUV) series.
My goal is that this review only covers the 50 SUV series muffler, which is rated by Flowmaster as a mild sound on their sound level scale chart.

Overall it cost about $200 to install. This included the muffler, installation and my decision to redirect the pipe over to the side of the truck behind the tire eliminating the resonator, which involved some extra 2.5 tubing and welding a hanger in place. I'll post some pictures below this review tommorow. This type of install is something that any muffler shop should be able to do with ease. Just go to a place you know and trust or ask around town who does good work.

So how does the 50 SUV sound and perform...

When I got to the shop to pick my V6 4runner up, they had just finished and it was running in the parking lot. I couldn't hear anything different. Honestly I went into a little panic thinking NO it's too quiet and doesn't sound any different. When your 4th gen 4runner has this muffler it will sound the same while the truck is at idle.

I jumped in and gave it some gas.........it sounded great. Very low rumble and this muffler really resonates at the bottom end of your throttle range. The sound is low, deep and robust. As I drove away it was very apparent that it was no longer sounding stock. As the RPMs increased through the throttle range it quickly started to quiet down and then if I really got on the throttle it piped back up. The best way to explain this is to graph a smile, with the verticle measure being sound level and the horizontal being the rpm range. Low low rumble during takeoff and then it mellows out only to spike back up if you gas it hard.

I like that it is quiet while idealing, this is good for the people next door and warming the truck up. The startup sounds great before the RPMs drop back down and if you hammer the throttle it opens up with a nice throaty roar and no longer sounds like a jet taking off.

As far as drone goes, this muffler does not drone...it is just much louder in the low RPM range than the stock muffler. "Droning" is not correct terminology for people that hate the sound of a muffle that runs louder than stock. Again I don't think this drones, its just louder than stock.

If you want a quiet ride, don't get this muffler, don't get any aftermarket muffler. It will bug you and if your not interested in hearing your engine, then it is a pointless upgrade.

If you want an aftermarket sounding truck and want to actually hear what your engine is doing, but don't want anything extreme, this is a good choice in my opinion. It is a quiet aftermarket muffler compared to many, but it's more robust sound characteristics gravitate toward the bottom and top end of your truck's RPM range.
Yes... it sounds BADASS
No.. it won't rattle your teeth out
Yes.. it will bother your wife and newborn.
No... it won't be louder than the sound of your tires and stereo at moderate volume levels while at cruising speeds. I noticed this muffler is louder during in town driving than on the highway.
I think it is the best of both worlds falling somewhere between the stock sound and most aftermarket mufflers out there.

Performance....absolutely nothing in HP, but it will put you much more in touch with how and where your engine is running. Very useful while doing any technical driving.

Thats it, I will post some pics next and I hope this is helpful to anyone interested in a Flowmaster 50 SUV muffler.

Great analogy with the smile! I'm running a super 40 on my v6, although I feel it's a bit too quiet. You can definitely hear it inside the cabin when your music is moderately low. Although, it barely hits the low throaty noise you are refferring to unless you really punch it. Don't get me wrong, it's definitely there, but you won't be hearing me from 100 yards away. It sounds the best in the range of 1200-1600 revs. Have you heard both the 40 and the 50? Great review! Makes me want to switch.

ive been running the 50 SUV series on my 4.0 0'3 for amlost a year with different cats ..
i love the sound, nice deep and throaty not a v-8 sound though , yet still toyota power that i can hear pretty far away unlike the super 40 that sounds like a import tuner haha

Yes the 50 SUV has a very deep sound. I didn't tell my wife about the install...big surprise. She took the truck last night to a friends house, I got a call about 30 min later with a "what did you do". I said to her " what are talking about", she replied.. "you just couldn't leave it alone, could ya."

Case in point, this muffler is noticably louder to the untrained ear, but since she is letting me keep it, it lets me also know this muffler is nothing too loud and is something we can live with in day to day use.

Good Review, you think it would have to same effect on the V8?

The V8 runs nice and quiet, just a little quieter than I would like and was thinking of something that would give it a little more 'feeling' and your review makes me interested in a muffler swap.

I think the V8 would sound amazing with this muffler. But it will be louder than stock. If you know anyone with an aftermarket muffler go for a ride and see how you like it.
I think alot of people will upgrade the mufflers on their their pickup trucks, but because the bed is separate from the cabin of the truck, which is not directly over the muffler, it tends to be quite a different experience than the same muffler on an suv/ 4runner, where the muffler is directly below the cabin.
I drove the 4runner again today around town and the FLowmaster 50 SUV is quite liveable. If you don't want to hear the muffler, just put on some music, and you don't need to blast the stereo or anything.
I have to say though, I wasn't listening to the stereo very much...just the sweet sound of my new muffler.

Also, people that don't reroute the pipe around the side and maintain the resonator will probably have an even more mellow sound.
If you put one on your V8 let me know how it sounds.

Just want to let everyone know that I am currently driving my 4runner from Cali to Maine to relocate with my family. So far we have done Zion, Arches, Moab.....loving every mile.
I now have some decent experience with this muffler and I am still very impressed with the tone and livability of it. No droning on the highway.

I am writing this post if anyone is interested in this exhaust and tows often. I want to point out that the increase in RPMs due to the tow load does not make the muffler any louder, it actually quiets is down because the RPMs are higher and the muffler is loudest at low RPMs. Anyway this muffler is still great IMO after a few thousand miles and sounds great.

Also a side note as far as pulling a trailer with the V6, this truck is a beast. I am pulling 5000 pounds and just went over the Vail pass in Colorado. No problem.
Because of the ATRAC system and sport model the brakes are awesome and I have not had a single issue towing with this truck. I did install a big ass tranny cooler to be safe, but I am just impressed with this 4runner in everyway. The rest is all downhill from here to Maine.