Exhaust MagnaFlow mufflers w/5.3 swap?

[UniqueOdyssey68]

Anybody have any videos of 14 inch MagnaFlows with a Gen III 5.3?
Searched a lot here and youtube and not much of this specific setup or it's not mentioned.
Getting custom exhaust done soon. 2.5 inch Dual 14 inch long oval MagnaFlows behind cab tucked into frame, H pipe. Not cats, just running straight out back under bumper (tip cutouts) to 3.5 inch rolled edge stainless tips. Headers are shorty's on a 2006 5.3 (L33 "H.O.") stock w/custom ecm tune.

Can't decide between 14 inch or 18 inch long MagnaFlows, but I'm thinking 14. I'm hoping for good flow, low restriction (LS engines like to breathe), Noticeable idle/rumble, enough to hear across the street (residential) or standing nearby but not streets over the whole neighborhood lol, and that smooth deep tone on acceleration, and aggressive on WOT. From the tons of reading and research I've done, dual magnaflows with minimal bends, straight and H pipe seem to be the way to go. I love the Flowmaster idle sound, burble, but I think in these single cabs and overdrive cruising RPM most Flowmaster's are to loud, drone a bit much and definitely don't flow as free as straight thru.

Any links to videos of Gen3 5.3 stock with 14 inch MagnaFlows would be greatly appreciated. Thank you!

[mongocanfly]

I can't help you with a video...but, I have a set of 16in magflows on my 6.0 swapped C30..
Notice I said magflow, not magnaflow.. no X or H pipe
they are identical to each other, just knockoffs..but much cheaper,
since changed the name to maxflow..
Running 2-1/2" from headers ,,,dumps in front of rear axle.. I love the way it sounds.rumbling idle, good sound at highway speed.. flow is great..get lots of "I love the way your truck sounds" compliments
I think you'll be pleased with the results on your truck, I think I'd go with 18s over 14s

[bigmoe]

My stock Gen IV 5.3 has shorty headers, duals with no x/h pipe, Magnaflow XL 3 chambers and tailpipes over the axle and out behind the wheels. Love the sound on start up and slow power. Don't really like the hard throttle because it's quite "plappy slappy", not what I would call smooth and deep. I added some cheap resonators under the cab before the mufflers but it didn't really change it much. It's okay but I wish it was deeper and throatier.

[truckster]

I can maybe post some video tomorrow... I put 2 1/2 inch stainless duals with an H pipe and 14" Magnaflows on my Blazer a couple of months ago. It's an L31 rather than an LS, but I love the sound. Low rumble at idle, sounds sweet running through the RPM range, and thunders a bit at wide open throttle.

[UniqueOdyssey68]

Thanks! The straight thru designs seem to produce that deep tone at idle and accelerating I like.

Originally Posted by mongocanfly

I can't help you with a video...but, I have a set of 16in magflows on my 6.0 swapped C30..
Notice I said magflow, not magnaflow.. no X or H pipe
they are identical to each other, just knockoffs..but much cheaper,
since changed the name to maxflow..
Running 2-1/2" from headers ,,,dumps in front of rear axle.. I love the way it sounds.rumbling idle, good sound at highway speed.. flow is great..get lots of "I love the way your truck sounds" compliments
I think you'll be pleased with the results on your truck, I think I'd go with 18s over 14s

[UniqueOdyssey68]

Hmm, from all the tech articles I'm reading and what MagnaFlow tech support emailed me today, the lack of a balance pipe (either H or X) on the LS/Vortec series engines is what is causing that "slappy" noise during hard throttle which is high in the RPMs. Those balance pipes are recommended for reasons to balance the exhaust pulses and even out/"smooth" the turbulence as the exhaust passes down the pipes. Might consider adding one and see if that helps yours, it should..
On the older SBC and BBC etc. this wasn't as much of an issue and actually produced a nice uneven "roar" pulse at high RPM, but the exhaust stroke scavenging and cam profiles are different in the LS. Reading up on this stuff has been kinda fun lol.

I think I'm going H pipe it seems to be less cost than a X pipe.
Thanks for the info on your setup.

Originally Posted by bigmoe

My stock Gen IV 5.3 has shorty headers, duals with no x/h pipe, Magnaflow XL 3 chambers and tailpipes over the axle and out behind the wheels. Love the sound on start up and slow power. Don't really like the hard throttle because it's quite "plappy slappy", not what I would call smooth and deep. I added some cheap resonators under the cab before the mufflers but it didn't really change it much. It's okay but I wish it was deeper and throatier.

[UniqueOdyssey68]

Nice! Much like what I'm thinking. H pipe takes up more space but costs less and is "supposed to" help in the lower RPMs compared to the X in higher RPMs. This will be a street driver so lower RPM flow is better
Videos would be great if you have them, thanks!

Originally Posted by truckster

I can maybe post some video tomorrow... I put 2 1/2 inch stainless duals with an H pipe and 14" Magnaflows on my Blazer a couple of months ago. It's an L31 rather than an LS, but I love the sound. Low rumble at idle, sounds sweet running through the RPM range, and thunders a bit at wide open throttle.

[Richard]

If you love the Flowmaster sound use the 70 series. Same sound but about 50% quieter. Have single 3" on my 94 and get compliments often. They are a bit longer than the others. On any muffler regardless of design, larger usually means quieter. Probably going use two 3" 70 series with an X-pipe on my LSA installed in the 72. HP loss or gain is not a concern for me. Even at 650 or so at the crank, type of muffler would maybe account for 10hp 1 way or the other. Probably no change at all because motor has a supercharger.

[verdell]

Originally Posted by UniqueOdyssey68

Anybody have any videos of 14 inch MagnaFlows with a Gen III 5.3?
Searched a lot here and youtube and not much of this specific setup or it's not mentioned.
Getting custom exhaust done soon. 2.5 inch Dual 14 inch long oval MagnaFlows behind cab tucked into frame, H pipe. Not cats, just running straight out back under bumper (tip cutouts) to 3.5 inch rolled edge stainless tips. Headers are shorty's on a 2006 5.3 (L33 "H.O.") stock w/custom ecm tune.

Can't decide between 14 inch or 18 inch long MagnaFlows, but I'm thinking 14. I'm hoping for good flow, low restriction (LS engines like to breathe), Noticeable idle/rumble, enough to hear across the street (residential) or standing nearby but not streets over the whole neighborhood lol, and that smooth deep tone on acceleration, and aggressive on WOT. From the tons of reading and research I've done, dual magnaflows with minimal bends, straight and H pipe seem to be the way to go. I love the Flowmaster idle sound, burble, but I think in these single cabs and overdrive cruising RPM most Flowmaster's are to loud, drone a bit much and definitely don't flow as free as straight thru.

Any links to videos of Gen3 5.3 stock with 14 inch MagnaFlows would be greatly appreciated. Thank you!

I'm running a cammed L33 with Magnaflows, 2.5" exhaust, X-pipe, all the way out back dumping under the roll pan, stainless tips. I know it's not your exact setup but may give you an idea. I'll message you if you like..

[LS short box]

Pic of my Magnaflow like mufflers installed. Didn't care for the sound. Went back to my old stand by Dyno Max turbo mufflers.
Typically I run 3" to the mufflers from the headers. Then 2.5" tail pipes.

[fourspeedwagon]

Unique— What did you wind up using? Happy with it?

[UniqueOdyssey68]

Originally Posted by fourspeedwagon

Unique— What did you wind up using? Happy with it?

Yes, went with dual 14x9 MagnaFlows straight out back to bumper cutouts. It looks pretty good, and it's tucked up into the frame. I'll post pics soon.