Magnaflow Muffler

travishale84 · March 5, 2011

so i just bought my very first magnaflow muffler. I used to buy nothing but flowmaster. loved the way they sounded on the outside, but that interior drone was enough to drive me to drink some days. i got the si/so 3" 4x9 20" oval muffler. should flow much better than any flowmaster ever did. i also got a 2 3/4" id x 12" slant summit racing tip.

should be here on tuesday, and im excited for this. although i have heard magnaflows aren't that loud. im not usually someone to try something new, but i want this muffler to last, have little to none interior drone, and give my 4.8 the voice it needs.

for future mods im planning on the zone 2" lift mainly because of the price for a front spacers, and rear lift blocks with U bolts.

tyhuck · March 5, 2011

with the 20" case that you ordered it wont be loud, but you will know its not stock. I have the same muffler with a 24" case, and its just a touch louder than stock at idle, but it will roar at higher RPM. I had a 14" case on my 06 2500, and It was loud, but I liked it. It did tend to make it hard for people in the back seat to hear what people in the front seat were saying though. Ide say you will probably like the 20" case.

travishale84 · March 9, 2011

so i installed my 14" magnaflow on my 2011 sierra with the 4.8. i gotta say its only slightly louder than stock at idle (just like everyone said) but as soon as you step on it, you can really hear the exhaust. cruising from 1000-1500 you cant even hear the magnaflow. at a steady speed from 2000-2500 its definately louder than stock, but not obnoxiously so. when you hammer it the magnaflow comes to life! definately glad i didnt go with anything bigger from magnaflow.

SpeedyV · March 10, 2011

so i installed my 14" magnaflow on my 2011 sierra with the 4.8. i gotta say its only slightly louder than stock at idle (just like everyone said) but as soon as you step on it, you can really hear the exhaust. cruising from 1000-1500 you cant even hear the magnaflow. at a steady speed from 2000-2500 its definately louder than stock, but not obnoxiously so. when you hammer it the magnaflow comes to life! definately glad i didnt go with anything bigger from magnaflow.

Sounds like it came out the way you wanted.

I actually just had a Magnaflow exhaust put on my 1500HD today (5 x 8 x 18" muffler case with 3" dual inlets/outlets, swaged down to 2.5" duals from the muffler to the rear with 3.5 x 18" Magnaflow slant-cut tips). Sure woke the 6.0L up

bones30 · March 26, 2011

SpeedyV,

I also have an 03 1500hd, and did virtually the same exhasust set up but noticed very minimal gain if any mainly just sound. Where did you notice a gain? You have 3.73 gears I assume? Are you pretty happy with the performance

Thanks

Sorry noticed you 4.10s maybe thats the difference

SpeedyV · March 26, 2011

SpeedyV,
I also have an 03 1500hd, and did virtually the same exhasust set up but noticed very minimal gain if any mainly just sound. Where did you notice a gain? You have 3.73 gears I assume? Are you pretty happy with the performance

Thanks

Sorry noticed you 4.10s maybe thats the difference

The most significant difference is the sound, of course. I love the rumble off idle, and it sounds great wide open - without being too loud. It does make a lot of noise in the range of 1400-1800 RPM when under load (e.g. in OD at 45-50mph while climbing a hill), especially when the truck hasn't warmed up, and I'm strill trying to decide if that's a good thing or if I should consider adding a resonator. The neighbors might not like that in the morning Then again, it has mellowed out a bit over the past few weeks...or maybe I'm just getting used to the new sound!

Performance-wise, I can tell the truck breathes better. It cruises just a bit smoother at high speeds, goes into OD more quickly, wants to "go" from a stop, etc. But the difference would be hard to quantify.

Black Bear is coming to town in May, and the exhaust was just one pre-tune step. I've changed all fluids and filters, cleaned the MAF and throttle body, and (just today) ordered new plugs. I bought this truck less than a year ago, and it now has 106K miles, so I'm just going through everything to try and get it in top condition...