Magnaflows.... Do they resonate in the cab?

sxmax · January 14, 2005

He said that if you go with a single magnaflow muffler with a dual in and single out you will get bad cab resonation with a 6.0 or 8.1 ltr at constant speeds. Everything I read says no.... He said they did some tests on a 6.0 and the only way they could get rid of resonance was to put dual muffler and dual pipes, which I do not want..... Any truth to this??? I was thinking about doing dual 3" inlets and 3.5"outlet???

GMCSierra04 · January 14, 2005

I have their 3" single exit cat-back (22" muffler) and from about 1500-2200 rpm's its quite noticable, especially when you drive 800 miles with it. I'd look around if I were you. I kinda wish I would have gotten Corsa but the price is a real deturent. Good luck.

LikeaRock14 · January 14, 2005

A few members at CTW have ran their 6.0 liter w/ the 5X11X22" case Magnaflow muffler and have had very good luck as far as resonance. One member just bought a Sierra Denali w/ this mufffler, and he said it's almost unnoticeable at cruise speeds

The 6.0 is a loud motor and has had resonance issues since day one unfortunately, and manufacturers have been trying to make a muffler to control the resonance. So far, the 5x11" Magnaflow muflers seem to do a fairly good job

teamjnz · January 14, 2005

He said that if you go with a single magnaflow muffler with a dual in and single out you will get bad cab resonation with a 6.0 or 8.1 ltr at constant speeds. Everything I read says no.... He said they did some tests on a 6.0 and the only way they could get rid of resonance was to put dual muffler and dual pipes, which I do not want..... Any truth to this??? I was thinking about doing dual 3" inlets and 3.5"outlet???

<{POST_SNAPBACK}>

I have a 6.0L Silverado with a MagnaFlow P/N 12198, 5X8 oval X 14" long, dual in and single out. It sounds great!!. It has a deep throaty sound. Not loud and obnoxius, but sounds cool. The cab resonation isn't bad in my opinion. It is around ahh don't remember... 1200 to 1500 RPM?? cruising with a lite acceleration. It still sounds cool and authoritive. It is nothing like the FlowMaster we have on our Suburban which is starting to annoy me now.

teamjnz

99GMCZ71 · January 14, 2005

YES!!! I know from experience.

Roostman · January 14, 2005

I have the 22" or 24" MagnaFlow and IMO, it sounds great. Pretty much any performance muffler is going to give you some noise, but in a v8, thats a good thing. Like Teamjnz said, from around 1600-2200 RPMs at LOW speed, it sounds kinda loud (I personally think it sounds great in that range though) but once on the highway in that RPM range, you wont here it at all, only when you shift into passing gears will you here it on the highway. Overall, its a good balance of sound and performance that you would probably be happy with, but I dont know you or what your looking for as far as your exaust setup goes. Good luck.

sxmax · January 14, 2005

Roostman. I pretty much have the same setup as you. What did you do for a muffler? Dual 3" inlets and single 3.5" out? Let me know. I just want to make sure it is not going to drive the wife crazy. I just feel with the large dual inlets and the small single outlet it is holding the engine back from power and even some mileage gains at highway speeds.

Roostman · January 14, 2005

Yeah, Im pretty sure I got the dual 2 3/4" (same as the incoming pipes) and a single 3" out with a mandrel bent 3" pipe to the rear. I wouldnt worry about restricting the exaust with this setup cause its a straight through design. Besides, there needs to be some restriction for the exaust for some scavenging I believe. Too free and I dont think the motor burns quite as efficiently (in the case of production vs. a race built motor that is designed to burn with a short pipe exaust ie. dragsters). I could be wrong on this though but pretty sure its the right idea. Anyway, going too big over the stock incoming pipes wont gain much if anything IMO.

SS Crew · January 14, 2005

Magnaflow makes a stainless steel 5"x 11" muffler with dual 2-3/4" in and 3" out and is 30" long, part # 14592. This might be the way to go. I've been hemming and hawing about this muffler, but I don't want the d*mn resonating in the cab or the droning at cruising RPM.

Does anyone have any 1st hand knowedge about this muffler?