I really dont think the flowmaster will be that ricey on your v6. Depends on the piping. Just dont go too big.
On my 4 cylinder i had the 40 series flowmaster and then found out it was a knock off, but really the same exact thing. I had something break inside the flowmaster and ended up trying a magnaflow. All I can say is mine hasn't completely broken in yet, but its definitely not as loud as the flowmaster. Its a lot quieter in the low revs but still is there when you step on it. I will also say that the magnaflow has practically no resonance so thats why i also think its not as loud inside the cab. I still havent had someone drive by me so i can here it yet. Remember that I have a 4 cylinder with headers and an intake though, anything will sound better on a V6.
My main comparison will be this. The magnaflow will not be as loud inside, it has a more low smooth growl, but really isnt that loud. Thats the only reason I dont like it on my 4 cylinder. Now, the flowmaster is more of a crackly roar that I actually liked better. It was a lot louder with resonance in the cab as well which I actually liked. However, it did sound a tad ricey once I past like 4,000RPM with the manual in my 4 cylinder. Then there is always that flow/backpressure issue that everyone talks about where to me it looks like a magnaflow flows a lot better than a flowmaster, just by looking through them and seeing the design. So flowmaster more backpressure and low end/ magnaflow more flow and top end. I really couldnt tell the difference between just swapping out the two different mufflers as far as performance.
Now just remember this is my very non professional learnings. Just what I have kind of concluded of having both on my 4 cylinder. Im sure on the v6 they'll both sound alright. It depends what you want. The performance gain of any muffler on these trucks is not even going to be noticeable. Maybe noticeable when you change pipe size and the muffler. But really Im assuming were going for just sound like I mostly did on my truck.
SOOOO, for the magnaflow/ flowmaster decison I would say if you want a loud nice sounding aggressive exhaust go for one of the flowmasters. I actually like them that way. If you want a nice smooth sounding low growl with no interior resonance but not that much louder than stock then go with the magnaflow. Hope this somehow helps.
Another tip, your only getting a real flowmaster if it has the flowmaster name stamped next to the weld on the muffler. If thats not there it could still be the same thing, but you definitely have a knock-off and not a genuine flowmaster with the warranty and all that.
