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· B4U Task Force
35,580 Posts
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.


· B4U Task Force
35,580 Posts
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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· B4U Task Force
35,580 Posts
@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.


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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