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Discussion Starter · #1 · (Edited)
Hey all,

I am battling myself over which exhaust setup to run for the looming LS3 swap on the 2003 Blazer X in my sig. Hoping to tear into this in mid-late March.

Any photos out there of any Gen2 Blazer exhaust systems?

Obviously a lot of pickups out there, but not too many Blazers. There is not much room on the left/driver side to run any pipes due to the vapor cannister/etc. that sits next to the leaf spring. Fuel tank is in the rear on Blazers vs the side tank on pickups.

The reason I am looking at these dual Magnaflow 4" mufflers instead of a dual in and ingle out is because all of the reviews say that these are the quietest mufflers out there. I am trying to keep this from being completely annoying. Between the cats, mufflers and resonator, I think this would be very tolerable - even at 545hp.

Assuming that I need to run this to a single exit on the right side, my current idea is as follows:
  • I am really trying to cut as much drone as possible and the same Ultra-Quiet resonator absolutely KILLED the drone in my Titan with long tubes and a full 3" system.
  • The Y after the mufflers is different, but is a common setup in late model trucks. This is the only way I can think of to get the resonator in there. Plenty of room on the right side.
  • I would love to fit an X-pipe, but won't know until I get everything in place. If I can make it fit, it will be there between the cats and mufflers.

3" from headers to tailpipe
Headers - Holley 70201316-r - 1 3/4" Mid-length Stainless - Just got them back from Jet-Hot - Pic below
Cats - Magnaflow 447209 Universal 3" - CARB approved (required in Colorado - don't get me started :rolleyes:)
Mufflers - Magnaflow 14419 Performance Mufflers - 3" in and out.
Resonator - Vibrant Ultra-Quiet 1142 - 3"

Any feedback and photos are appreciated!


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Just got these back from Jet-Hot - Came out nice.
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Here is his build thread maybe give it a gander.
 

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LS3 545hp
at that low of hp, you dont need dual 3".. 2.5 will be fine and quiter.
you can run the 2.5s into eachtoerh and a single 3 out like your picture use borla or magnaflow muffs.
how are you getting 545 hp?
 

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Discussion Starter · #5 ·
LOL! Cracks me up. I am still so old school and think that 545hp sounds like a lot. :ROFLMAO:

Was wondering on the 2.5" vs. 3". I was guessing a difference of may be 20hp.

The 545 comes from the actual dyno sheet from Blueprint.

The only actual thing that I am waiting for to start the swap is the transmission from Chuck at Finish Line. Should literally be done any day now. He has my Circle D Billet converter for the dyno test. (y)
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I am still so old school and think that 545hp sounds like a lot.
i know crazy eh?
in the 80s if you have 500 hp you were a demigod..
nowadays if you show up to the local hang out under 1200 WHP youre just a poser.
that is a nice engine though, itll make your blazer a fun cruiser
 

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Hey all,

I am battling myself over which exhaust setup to run for the looming LS3 swap on the 2003 Blazer X in my sig. Hoping to tear into this in mid-late March.

Any photos out there of any Gen2 Blazer exhaust systems?

Obviously a lot of pickups out there, but not too many Blazers. There is not much room on the left/driver side to run any pipes due to the vapor cannister/etc. that sits next to the leaf spring. Fuel tank is in the rear on Blazers vs the side tank on pickups.

The reason I am looking at these dual Magnaflow 4" mufflers instead of a dual in and ingle out is because all of the reviews say that these are the quietest mufflers out there. I am trying to keep this from being completely annoying. Between the cats, mufflers and resonator, I think this would be very tolerable - even at 545hp.

Assuming that I need to run this to a single exit on the right side, my current idea is as follows:
  • I am really trying to cut as much drone as possible and the same Ultra-Quiet resonator absolutely KILLED the drone in my Titan with long tubes and a full 3" system.
  • The Y after the mufflers is different, but is a common setup in late model trucks. This is the only way I can think of to get the resonator in there. Plenty of room on the right side.
  • I would love to fit an X-pipe, but won't know until I get everything in place. If I can make it fit, it will be there between the cats and mufflers.

3" from headers to tailpipe
Headers - Holley 70201316-r - 1 3/4" Mid-length Stainless - Just got them back from Jet-Hot - Pic below
Cats - Magnaflow 447209 Universal 3" - CARB approved (required in Colorado - don't get me started :rolleyes:)
Mufflers - Magnaflow 14419 Performance Mufflers - 3" in and out.
Resonator - Vibrant Ultra-Quiet 1142 - 3"

Any feedback and photos are appreciated!


View attachment 371670

Just got these back from Jet-Hot - Came out nice.
View attachment 371671
View attachment 371672
Check out Connor94's thread. He pulled it off nicely. It's 10 pages long but worth the read. Here's a link.

 

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Discussion Starter · #8 ·
Thanks for the feedback and info everybody. Just went through Harley's and Connor94's posts. Very cool! Those are the same mufflers I am looking at in Connor's post.

I will be using the full Holley LS swap kit. Will need to get everything installed and then think through all of the details once I can see and fit things.

I will most likely lay everything out with the kids pool noodles, zip ties and duct tape. Dumb as it sounds, it actually makes it very easy to mock up a full exhaust setup. 😆
 

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After already spending a bunch of money, you might consider the Hooker manifolds. There are no clearance issues, and if you have them ceramic coated, they'll reduce temps by about 200*
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Actually, the rule of thumb & with many charts published by exhaust & muffler manufacturers state 450HP is about the limit for dual 2-1/2" exhaust.

Also, you want to retain the 3" off the headers as it will act as a collector extension, boosting your mid-range torque... especially since your header primary tubes are somewhat short.

If anything, I would stick with what you have, but possibly go up to a single 3.5" tailpipe after the mufflers.
 

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@Connor94 just redid the system on his Blazer and it looks very nice. He tucked the cats up in the downpipe section coming off the manifolds, but I don't think this is as doable for you with the headers.

http://instagr.am/p/CnehqvpOZiP/

I think you're on the right path with the single out. It gets really crazy going for the traditional duals - one on each side. Could take a play from the 2000s era GTO and run two pipes on one side, but I believe a single 3 or 3.5 will be easier to package. The 3.5 could be very tight over the axle, though. I merged 2.5" into 3" without cutting any of the factory frame/crossmembers. I haven't worked out a tailpipe yet, so take that with a grain of salt.

I'm not currently running cats, but plenty of room for them along the transmission on my setup. I'll be adding some soon for visual inspection where I recently moved.

What transmission are you running? It will make a difference in how much space is available. My T56 and lower engine height pushed me pretty far back on the crossover, but I think there would still be room for an X pipe even if it's above the crossmember behind the trans.

There is room for 2 mufflers under there. Even if you went with an oval rather than a round muffler they could be turned and set next to each other. If I'm remembering correctly @greencactus3 did this on his ZR2 Blazer build.

With all that said, I'm not sure where the resonator will fit behind the mufflers. Specs show it will end up being 10-13" long and there just isn't a straight piece of the tailpipe anywhere near that long. On @Rhotpursuit pursuit S10 we started out with one muffler, but he ended up getting 2 packaged in there and is much happier with the sound/drone. If it were my truck with the same goals I'd be trying to pack as much muffler x2 in there as I could.
 

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@Connor94 just redid the system on his Blazer and it looks very nice. He tucked the cats up in the downpipe section coming off the manifolds, but I don't think this is as doable for you with the headers.

http://instagr.am/p/CnehqvpOZiP/

I think you're on the right path with the single out. It gets really crazy going for the traditional duals - one on each side. Could take a play from the 2000s era GTO and run two pipes on one side, but I believe a single 3 or 3.5 will be easier to package. The 3.5 could be very tight over the axle, though. I merged 2.5" into 3" without cutting any of the factory frame/crossmembers. I haven't worked out a tailpipe yet, so take that with a grain of salt.

I'm not currently running cats, but plenty of room for them along the transmission on my setup. I'll be adding some soon for visual inspection where I recently moved.

What transmission are you running? It will make a difference in how much space is available. My T56 and lower engine height pushed me pretty far back on the crossover, but I think there would still be room for an X pipe even if it's above the crossmember behind the trans.

There is room for 2 mufflers under there. Even if you went with an oval rather than a round muffler they could be turned and set next to each other. If I'm remembering correctly @greencactus3 did this on his ZR2 Blazer build.

With all that said, I'm not sure where the resonator will fit behind the mufflers. Specs show it will end up being 10-13" long and there just isn't a straight piece of the tailpipe anywhere near that long. On @Rhotpursuit pursuit S10 we started out with one muffler, but he ended up getting 2 packaged in there and is much happier with the sound/drone. If it were my truck with the same goals I'd be trying to pack as much muffler x2 in there as I could.
My original muffler was a Magnaflow with a built in X pipe....it was miserable. I ended up with 2 Hush Trush mufflers side by side standing on edge. An X pipe was added as far upstream as was possible. It sounds much better now and is barely audible at highway speeds. It still barks pretty good if I lean on it.
 

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Discussion Starter · #13 ·
Thanks guys. I appreciate the feedback.

Transmission = Level 5 - 4L65e (with Sonnax Housing and overrun clutch hub) from Finish Line. Should be ready any day now. I stayed with the 4L series due to simplicity and space concerns.

The only reason I am going to run cats is due to the new emissions laws coming down on Colorado. Nothing good to say here. When all is said and done, I am sure that I will have 2 exhaust setups. One through the cats and one without. I will set these up with V-Band clamps to make it easy. And 2 different ECU's that I can swap out as needed.

My plan is to run 2 of the Magnaflow 14419 mufflers in the configuration at the top of the thread. These are 3" in/out and only 4" around and can easily be used side by side. Even welded together into a single unit if need be. We'll see if there is any space to add an x-pipe.

Completely agree on the 3.5" tailpipe. This Blazer is really low and real estate is sparse. I may only be able to get a 3" pipe in there. I will keep hoping that I can get the resonator in there, but we will see.
 

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Discussion Starter · #15 ·
I wish.... I have similar on my Titan. Unfortunately, this will have to pass a visual, electrical and mechanical/sniffer test as well. I am going to have to tear everything out of the Titan as well (Long tubes, no cats, tuned) now that the Colorado smog cops are copying California regulations. It is not active in my county (yet), but it is coming soon. Hopefully it keeps getting challenged and meets legal delay after delay. We'll see.

The local exhaust shops can't even legally install my setup without brand new CARB approved cats. The state can shut them down - already happened to a few shops in Denver. Just friggin' ridiculous! I am still researching and am sure I can find somebody local to do it.

In the long run, I do plan on having 2 sets from the headers to the mufflers. One with cats and one without that I can swap out with V-Bands. We'll see...
 

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Transmission = Level 5 - 4L65e (with Sonnax Housing and overrun clutch hub) from Finish Line. Should be ready any day now. I stayed with the 4L series due to simplicity and space concerns.
There should be plenty of space to get around the transmission and have room for an X pipe. My experience with a 4L60 was on an S10, but it felt much roomier than my T56.

My plan is to run 2 of the Magnaflow 14419 mufflers in the configuration at the top of the thread. These are 3" in/out and only 4" around and can easily be used side by side. Even welded together into a single unit if need be. We'll see if there is any space to add an x-pipe.
There will be plenty of room for these mufflers. I made the suggestion to go bigger in case they're not enough without a resonator. There's tons of up/down, side/side, front/back where the mufflers will go. Not much space if any for the resonator in the tailpipe.
 

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Given the option, an H-pipe will mellow out the sound somewhat with the potential for increased mid-range torque.
The X-pipe may offer slightly better torque, but it will have more of a higher pitched/raspy tone than the H-pipe.

Keeping the mufflers towards the middle of the vehicle (usually just before the rear axle) tends to work best for sound control & always at least 2ft from the header collectors.
 

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Discussion Starter · #18 ·
Thanks guys.

The H pipe would save some space over an X. I am going to need to get the engine/trans installed and then try to lay everything out. Once I can see how the pipes run past the transmission x-member, it will give me a better idea.

My current plan is to pull the current drivetrain between March 15-17. My brother and a friend will be here and I am going to put them to work. :) A couple of local friends want to help as well. I am finally getting excited about this!
 

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Looks like @Harley gave up all my secrets! I hope that information helps. I hear you on the zero real estate under there, especially with it being low. For your volume goals, I think single is the way to go. I tucked my cats up tight but the cats you need to use won’t fit in that orientation, even assuming you swapped to manifolds. Those LS3’s love to breathe so you’re right on with 3.5”. My opinion, run 3” off the headers, cats, Y it after the trans crossmeber and go 3.5” back! Saves some money on buying 2 mufflers as well. My 3” tail pipe is tight, so the 3.5” will be tough but I honestly think it’s do-able depending on how low you actually are.

the reason I’m suggestion you run single 3.5 is due to packaging, and your volume goals! You’ll put down 450+ to the wheels and even at that level full dual 3” is a lot of exhaust. Trust me, building even a full stainless 2.5”dual exhaust is expensive! Should be photos of the second dual exhaust I made on my instagram as a well.
 

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Discussion Starter · #20 ·
Thanks Connor.

I am going to need to scope this out. 3.5 after the muffler(s) would be really tight. We'll see. All kinds of ideas and options.

Regarding the resonator (and stealing your IG image below), it will be interesting to see if one of the resonator options below would fit if the exhaust tip was extended a little farther toward the bumper.

The top one may be too tight, but the bottom one may fit perfectly.
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I have this one on my Titan. Killed all of the drone. Maybe fit mounted sideways?
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This one is very compact and may fit well.
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