I just got a 08 GMC Sierra Z71 4x4 with a 5.3. I am trying to get some ideas for a muffler. I want something that is going to sound good with good flow. I know in around Feb I will be goin with long tubes and a off road y pipe with no cats. I want something that will go well with that combo. I know a local muffler shop that can get me Magnaflow mufflers very cheap, but I have heard the 5.3 with differant types of flowmasters, and I do like how they sound, so I am undecided on what to go with.

 

I have LTs ORY w/no cats and I love my 18" magnaflow dumped, flowmasters sound good but lack on performance. I ran a flowmaster on my other truck and like the sound much better with the magnaflow, it's more throaty. At high rpms flowmasters are way too loud and poppy. my 2 cents, good luck

 

I have the Pacesetter LT's and their ORY with a 14" magnaflow. Its too loud right now, do you think the 18" magnaflow is much quieter than the 14" or should I go with the 22"? Quieter is better, but I don't want it too quiet. Thanks.

 

Its not that loud especially for having a bigger cam, but I had the 22" and it was barely louder the stock.

 

maybe consider borla, or dynamax too. Lots of companies with different sounds to go with.

 

LOL. I have the 22" magnaflow (P/N 12589) and it's way louder than stoctk, especially in the cab (resonance around 17-1800 rpm), but in terms of aftermarket mufflers I guess you could say it's quiet.

It has a nice low rumble too it when cruising. At idle it's just as quiet as stock basically. I'm more low key, but if your looking for attention out of the street do not get the 22". I'd go with the 18"

 

Thanks, I'm torn between the 18" and 22" magnaflows; common sense says to go quieter, if I want to go loud I can always put the 14" on. I use my truck as a daily driver and the resonance is getting old.

 

Also note I have 6 liter. I've read that they have much more resonance problems than the 4.8/5.3. It's really hard to say whether or not to go with 18" or 22". I didn't see any performance gains (that I can tell) switching from the stock to the magnaflow. So I think that's irrelevant in muffler choice. Bottom line if you want it a little louder than stock go with the 22". If you want more agressive go 18"

 

Thanks for the response guys. I decided to go with a Magnaflow 18". Besides the shop I am goin to is only going to charge me 100 dollars total for the muffler, and install.

 

Dual spintech prostreets no cats and 3" pipe dumped right underneath your seat, loud and aggresive at any rpm and only pops when you gear down