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Stock muffler hack

14K views 2 replies 3 participants last post by  drift.mechanic 
#1 · (Edited)
As some may know, the stock rear muffler on our cars is not a true dual muffler. I didn't like that, so I made mine a true dual straight through muffler.

The stock piping is about 2" so you will need 2" perf piping to replace the piping and chambers inside the stock muffler.
Buying perforated piping can be expensive and hard to find a vendor for. So I got two Thrush glasspacks (2"in, 2"out, and 25" oal) from the local parts store.
Then I chopped one end off and pulled out the perf pipe. What's nice is that the perf pipe in these glasspacks are not welded in. so if you cut it open like I did, you can just pop them out.


Then I cut off the top side of the muffler case.


Removed the nasty packing. It's a little damp and made my arms very very itchy. Wear protection! Also wear some type of breathing mask while cutting this bad boy up. It stinks!


Not everything is welded together inside the muffler. A lot of it is just press fit, so you have to take it apart by a certain section at a time. It sucks and you will get pissed at it. I used an angle grinder with a cut off wheel (about 10 cut off wheels when all said and done), a little bit of sawzall, and a lot of beating with a hammer.






Then to make the perf pipe fit over the remaining pieces, I made slits like so. Looks crude but who cares? This part is getting welded anyway.


Now if you wanted a stock looking muffler that's actually kinda loud, you could just weld the case back on right now and call it good. Would probably sound like balls and be raspy as hell, but maybe that's what you want.

I wanted it to be quiet, so I packed it with this stuff.


I got a big @$$ roll because I for some reason like making mufflers.


Then I wrapped each perf pipe, also wrapped some old welding wire around them to hold it together, and layed a piece down under them.
Then weld the perf pipe to the remaining stock muffler inlets and outlets. You don't need to be able to weld all the way around. Just get what you can and get it good.


Then I added a bunch of layers of packing. I also put in all of the packing from the two glass packs.



Then weld the case back together.
I was using flux core wire with a MIG, so the welds didn't turn out the best. Had the heat turned all the way down and still burnt through just making tack welds. No worries, I put some liquid metal over all the welds to fill in the pin holes and called it good. The liquid metal made my welds look even worse, but I don't really care. You can't see it when it's mounted on the car anyway. It's sealed, so it's all good.


Results: It's quiet! Little louder than stock but hardly from what I can tell.
I'm very surprised how quiet it is. I do a lot of highway driving so no exhaust drone is cool with me.

Before


After
 
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