LOL. No offense to anyone, but i always find it funny how people always run to Flowmasters as if they were the only muffler out there....

Like lemmings running to the ravine.

Is this truck daily driven? If so Stay away from flowmasters as you will be giving yourself a headache from resonance every time you get in your car.... Flowmasters (or Noisemasters as I like to call them) are cool on weekend cruisers where you only have to put up with the sound for short times... but drive with them all the time and you will hate them.

Dynomax Super Turbo- these sound real good, and not so loud you will be banging you head on the wall.

Dynomax UltraFlow- These are a little louder than the super turbo's but they are still quieter than the flowmasters, but they are a straight through muffler and they flow a lot better than the flowmasters.(better flow=more power)

Borla- Hands down, these guys make the best flowing and best sounding mufflers i have ever heard. Again, not crazy loud like flowmasters, but an excellent rumble

Magnaflow- Another straight through Performance muffler that flows better than flowmasters, and sounds about the same as the Ultra Flow

Hooker AeroChamber- These are similar to flowmasters in that they have separate chambers inside, and they have a wicked cool sound, Pretty loud though, almost up there with the flowmasters. No clue how well they flow.

Another thing to keep in mind... The CASE SIZE of the muffler makes a big difference in the sound level- The larger/Longer the case the quieter/mellower the sound will be. The smaller/shorter the case the louder the sound will be.

So if you don't want it crazy loud- get a large case muffler (ie 20" or so)

Size of the exhaust pipe is more dependant on the HP level of your car. Stock 350 chevy's (~250hp) usually didn't need much more than 2 1/4" pipes. Start pushing 300-350hp 2 1/2" pipes will help some, more than 350hp and 3" pipes would probably be useful.

If you go with a larger than needed exhaust pipe, you will lose some low end torque, so don't go bigger than you need.

-Ben