vdrumright Posted October 17, 2003 Report Share Posted October 17, 2003 Well, I'm kinda dissapointed. The low frequency interior resonance is terrible at low speeds. I'm glad I saved my stock muffler. Back to the drawing board. Flopro emailed me & said they did dyno testing on the muffler they designed for the 6.0. Hestated that they showed 25 hp gain. He also said the interion resonance is minimal. I'm just kinda having a hard time shelling out $300.00 for a muffler. What do you guys think. Here the new FloPro that is made specifically for the 6.0l chevy. Muffler Clip Link to comment Share on other sites More sharing options...
Black03SS_NJ Posted October 17, 2003 Report Share Posted October 17, 2003 The low frequency interior resonance is terrible at low speeds. I personally would not be bothered by low speed resonance...it's the high speed resonance with a high-flow exhaust that drives me nuts. That WAAAAAAAAA sound on the highway for an hour kills me. This is the only reason I have not swapped exhausts yet. Really sorry about your problem. Here's what I would try next, if you are dead-set on taking this system off: Flowmaster 50 Series Big Block. It is a dual 3" in / single 3.5" out which uses the stock tailpipe, made just for 6.0L and 8.1L GM trucks. You will lose your duals, but Flowmaster tells me that one tailpipe will not resonate like duals. You other option would be to add two resonators before the pro-flo. Those can be had for $40-50 apiece and may quiet things down a little, but I am not sure that there is room. You could also call pro-flo and ask if an x-pipe would help (not sure what the inside of the muffler looks like). But I bet you would hate to spend more $ on this system you are not happy with. Link to comment Share on other sites More sharing options...
vdrumright Posted October 17, 2003 Report Share Posted October 17, 2003 The low frequency interior resonance is terrible at low speeds. I personally would not be bothered by low speed resonance...it's the high speed resonance with a high-flow exhaust that drives me nuts. That WAAAAAAAAA sound on the highway for an hour kills me. This is the only reason I have not swapped exhausts yet. Really sorry about your problem. Here's what I would try next, if you are dead-set on taking this system off: Flowmaster 50 Series Big Block. It is a dual 3" in / single 3.5" out which uses the stock tailpipe, made just for 6.0L and 8.1L GM trucks. You will lose your duals, but Flowmaster tells me that one tailpipe will not resonate like duals. You other option would be to add two resonators before the pro-flo. Those can be had for $40-50 apiece and may quiet things down a little, but I am not sure that there is room. You could also call pro-flo and ask if an x-pipe would help (not sure what the inside of the muffler looks like). But I bet you would hate to spend more $ on this system you are not happy with. At highway speeds it is sweet sounding. not much louder than stock. But i can barely talk on a cell phone & have to turn the radio up half way at speeds between 25 & 50. Also, I have a 2 year old grandson that rides with me alot. I don't want to subject him to that kind of noise. Also, i know my GF is gonna complain. Where can i get these resonators your talking about? Link to comment Share on other sites More sharing options...
Black03SS_NJ Posted October 17, 2003 Report Share Posted October 17, 2003 I found the resonators here: Flowmaster Resonators. I would definitely talk to flowmaster first, before adding something like this. I am sure there are other resonator manufacturers, and an x-pipe may help. I would call pro-flo on that one. Again, I am not sure what is going to cure your "too noisy around town" problem, as most resonators and x-pipes quiet down noise at highway speeds. Your only option may be to swap out that muffler. But I would DEFINITELY give it the pro-flo a chance to break in, as the sound will change after a few weeks, for better or worse. Link to comment Share on other sites More sharing options...
m396 #00-011 Posted October 17, 2003 Report Share Posted October 17, 2003 Really sorry about your problem. Here's what I would try next, if you are dead-set on taking this system off: Flowmaster 50 Series Big Block. It is a dual 3" in / single 3.5" out which uses the stock tailpipe, made just for 6.0L and 8.1L GM trucks. You will lose your duals, but Flowmaster tells me that one tailpipe will not resonate like duals. Currently, Magnaflow suggests the same thing, for the exact same reason. Of course, it's their dual 3" in, 4" out. Link to comment Share on other sites More sharing options...
supraman Posted October 17, 2003 Report Share Posted October 17, 2003 I just added the Flowmaster 50 Series Big Block an love it......sounds awesome now. It has a nice rumble all the time now. Link to comment Share on other sites More sharing options...
vdrumright Posted October 17, 2003 Report Share Posted October 17, 2003 I went back to the muffler shop this morning & had the Flopro MX336 removed. Just for grins we put the stock muffler back on to see if it was a true dual in dual out. The results are: It's not. Looking at he rear of the muffler, the left side barely has any flow at all. Even when we covered the tail pipe on the right side flow did not increase. So for people looking to just add dual tail pipes & use factory muffler, don't. I took a hit for the team on this one......lol I'm gona leave it like this until I figure out what to do next. Link to comment Share on other sites More sharing options...
BenKey Posted October 17, 2003 Report Share Posted October 17, 2003 Finally, the old mystery is solved Link to comment Share on other sites More sharing options...
Black03SS_NJ Posted October 17, 2003 Report Share Posted October 17, 2003 I went back to the muffler shop this morning & had the Flopro MX336 removed. Sorry to hear about that. It looks like we all learned an expensive lesson at your expense. Link to comment Share on other sites More sharing options...
BigTex Posted October 17, 2003 Report Share Posted October 17, 2003 Crap! I had a feeling the stock muffler was just like some of the other 6Liters with one side closed off. Now I have a long tube headers flowing through mandrel bent pipes back to a restrictive single out muffler. So much for the sleeper look I was going for. I'm going to have to drop the stock muffler. I'm thinking about a new 3" dual in / dual out Magnaflow. I hear they have a new version that incorporates an X inside the muffler. Whatever I get, it will be the biggest that I can fit under there to cut out the drone. Will try to keep stock tip as well. Link to comment Share on other sites More sharing options...
BenKey Posted October 17, 2003 Report Share Posted October 17, 2003 Anyone thought of the Edelbrock brand mufflers? Buddy of mine had on his last truck. Sounded pretty awesome. Link to comment Share on other sites More sharing options...
Y2K Silverado Posted October 17, 2003 Report Share Posted October 17, 2003 The results are: It's not. Looking at he rear of the muffler, the left side barely has any flow at all. Even when we covered the tail pipe on the right side flow did not increase. I had a feeling it wasn't. The dual out mufflers on the Burb's, Ave's and Tahoe's aren't, the left side is actaully an inlet to a resonation chamber to keep the interior drone/resonation down. It must work pretty well, every muffler I've ever put on my silverado has resonated, that's why I wanted the SS muffler. It has a little rumble that I can hear but with no resonation which a major plus in my book. Jim Link to comment Share on other sites More sharing options...
rico750sxi Posted October 17, 2003 Report Share Posted October 17, 2003 At least I found out before I put the tailpipes on. Link to comment Share on other sites More sharing options...
m396 #00-011 Posted October 17, 2003 Report Share Posted October 17, 2003 Crap! I had a feeling the stock muffler was just like some of the other 6Liters with one side closed off. Now I have a long tube headers flowing through mandrel bent pipes back to a restrictive single out muffler. So much for the sleeper look I was going for. I'm going to have to drop the stock muffler. I'm thinking about a new 3" dual in / dual out Magnaflow. I hear they have a new version that incorporates an X inside the muffler. Whatever I get, it will be the biggest that I can fit under there to cut out the drone. Will try to keep stock tip as well. This is what I wanted to use as well. They guy on the phone recommended that if I "just have to use this one, get the big bodied one!" Needless to say, he tried his hardest to recommend against it. If you do, we need a full report with sound bites!!!! Link to comment Share on other sites More sharing options...
hatrack Posted October 18, 2003 Report Share Posted October 18, 2003 Crap! I had a feeling the stock muffler was just like some of the other 6Liters with one side closed off. Now I have a long tube headers flowing through mandrel bent pipes back to a restrictive single out muffler. So much for the sleeper look I was going for. I'm going to have to drop the stock muffler. I'm thinking about a new 3" dual in / dual out Magnaflow. I hear they have a new version that incorporates an X inside the muffler. Whatever I get, it will be the biggest that I can fit under there to cut out the drone. Will try to keep stock tip as well. BigTex this is the muffler I've been looking at from Magnaflow 3"/3" 12599+ it has the x built into the muffler. It is similiar to the stock or they have 3"/2.5" 12569+ . I wanted to stay with the stock look also. They have these at Big Exhaust for @ 98.25 and 89.95. Link to comment Share on other sites More sharing options...
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