I installed a Magnaflow muffler on my Avalanche last week. I purchased the muffler through TN AV03. He had installed this muffler on his Avalanche but then got a bead on a Corsa catback system and put his muffler and unused 3" tip up for sale for $75. Couldn't say no.
Overall Impressions Under The Av: I was shocked to see just how far back the muffler is on the Avalanche. Memo to self, if there is EVERY an exhuast leak around the muffler get it repaired immediately. I was impressed with the muffler placement, well out of the way for off-roading activity, it would take a very specific hit to damage the system. I was alarmed with the header coming off the driver side of the 5.3 liter V-8. I noticed it had been pounded flat and I was concerned that this had happened off-roading. The muffler guy told me that was "as designed" so it didn't hang down - however it made me wonder if the flow was restricted more coming off of the drivers side of the engine into the single exhaust.
Install: Had the install done but a local yokel chain called Bucky's. They do a lot of deep discounting advertising including Magnaflow mufflers for $59.95. Also did an oil change while there (Mobil 1 of course). The process took about an hour-and-a-half. Because the Magnaflow had been previously installed and had a small section cut off of it they had to do a small bit of pipe work. They replaced the section from the outlet that snakes over the axle - cost was $29.95. They charged one hour labor for the welding work (seemed high to me) for $70 so the whole install process with parts was $109.95. I wasn't thrilled with the cost but not horrified either. However I was EXTREMELY impressed that they brought me out to the shop and under my Av while it was on the lift to see the work they had done and ask me some questions on how to proceed with the install. You sure don't see that at many shops these days. The weld work was superb and clean - the guy clearly knew what he was doing and actually cared about his work. Kudos for that.
Sound: The sound from the muffler is excellent. On the outside there is a low growl at idle and although there is definitely a higher decibel level at acceleration is not obtrusive or offensive. Translation - flooring it in a parking garage does not set off sensitive car alarms. Cab noise is a different issue. Start up is incredible, there is a rumble in the cab that you can feel as you turn the key and as the engine idles down a faint growl. Under load things are pretty noisy between 1500 to 2000 RPM, more than I expected but not offensive. It is at it's loudest around 1,800 RPM. The noise isn't bad during highway cruising - only under load like hard acceleration or climbing a hill. Still I was under the impression that resonation from the Magnaflow was better than say the Flowmaster 50 series, which I've heard in cab on flyinhigh's Av - this seems a lot louder under load in a narrow band.
Performance: I think the install has hurt my performance in the area of starting torque. Low end torque is diminished to a noticable level. However the overall power curve seems a little wider and flatter with smooth power pulling over 2,000 RPM all the way to the 5,500 RPM shift point. I don't think that 0 - 60 time was seriously impacted, if at all - but low end grunt is reduced.
Conclusion: For $75 parts and $109.95 install I have no regrets. The sound is excellent without aggravating the neighbors. There is a decided and pronounced V-8 growl from the engine now. Low end grunt has suffered but the power curve SEEMS a little flatter and wider. The Magnaflow was GORGEOUS with it's glossy polished finish. If someone was doing it to get the sound I'd recommend. Not sure if it's the best performance mod bang for the buck if it's all you plan to do.
Anyway - that's my thoughts!
Overall Impressions Under The Av: I was shocked to see just how far back the muffler is on the Avalanche. Memo to self, if there is EVERY an exhuast leak around the muffler get it repaired immediately. I was impressed with the muffler placement, well out of the way for off-roading activity, it would take a very specific hit to damage the system. I was alarmed with the header coming off the driver side of the 5.3 liter V-8. I noticed it had been pounded flat and I was concerned that this had happened off-roading. The muffler guy told me that was "as designed" so it didn't hang down - however it made me wonder if the flow was restricted more coming off of the drivers side of the engine into the single exhaust.
Install: Had the install done but a local yokel chain called Bucky's. They do a lot of deep discounting advertising including Magnaflow mufflers for $59.95. Also did an oil change while there (Mobil 1 of course). The process took about an hour-and-a-half. Because the Magnaflow had been previously installed and had a small section cut off of it they had to do a small bit of pipe work. They replaced the section from the outlet that snakes over the axle - cost was $29.95. They charged one hour labor for the welding work (seemed high to me) for $70 so the whole install process with parts was $109.95. I wasn't thrilled with the cost but not horrified either. However I was EXTREMELY impressed that they brought me out to the shop and under my Av while it was on the lift to see the work they had done and ask me some questions on how to proceed with the install. You sure don't see that at many shops these days. The weld work was superb and clean - the guy clearly knew what he was doing and actually cared about his work. Kudos for that.
Sound: The sound from the muffler is excellent. On the outside there is a low growl at idle and although there is definitely a higher decibel level at acceleration is not obtrusive or offensive. Translation - flooring it in a parking garage does not set off sensitive car alarms. Cab noise is a different issue. Start up is incredible, there is a rumble in the cab that you can feel as you turn the key and as the engine idles down a faint growl. Under load things are pretty noisy between 1500 to 2000 RPM, more than I expected but not offensive. It is at it's loudest around 1,800 RPM. The noise isn't bad during highway cruising - only under load like hard acceleration or climbing a hill. Still I was under the impression that resonation from the Magnaflow was better than say the Flowmaster 50 series, which I've heard in cab on flyinhigh's Av - this seems a lot louder under load in a narrow band.
Performance: I think the install has hurt my performance in the area of starting torque. Low end torque is diminished to a noticable level. However the overall power curve seems a little wider and flatter with smooth power pulling over 2,000 RPM all the way to the 5,500 RPM shift point. I don't think that 0 - 60 time was seriously impacted, if at all - but low end grunt is reduced.
Conclusion: For $75 parts and $109.95 install I have no regrets. The sound is excellent without aggravating the neighbors. There is a decided and pronounced V-8 growl from the engine now. Low end grunt has suffered but the power curve SEEMS a little flatter and wider. The Magnaflow was GORGEOUS with it's glossy polished finish. If someone was doing it to get the sound I'd recommend. Not sure if it's the best performance mod bang for the buck if it's all you plan to do.
Anyway - that's my thoughts!
