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Home made 3" cat-back! Just finished...

5.9K views 35 replies 26 participants last post by  derek  
#1 ·
Ingredients:
3" straight through dynomax muffler from Jegs ($30)
4' 3" pipe ($15)
2 mandrel 3" U-bends ($50)
Random 3" tip ($25)
Home made 2 bolt flange (because I couldnt find one)
Hanging hardware ($20)

It also cost me a little extra, because I had one friend make me the flange, and another helped me with the cutting and spot welding so I bought them dinner. Then the final welding cost $25

Total cost: around $200
Total time: about 3-4 hours building, and another hour for welding. And I assume it will take me another hour to hang it properly and weld the hangers on it.
Anyway here are some pics of it...
Here are the basic pieces:
Image


Here they are fit together:
Image


And here they are after the final welding. We painted the welded areas so they wouldnt rust.
Image


Tomarrow I am going to test fit it, and figure out where to weld the hangers, and after the hangers are on it I will paint it.

Anyway tell me what you think....hopefully I can have a video clip of its sound soon.
 
#8 ·
Well I got it on now, and its actually not all that loud, but it sounds pretty good.
It should be a little louder when I replace the cat with a test pipe.
But at any rate its super quiet when compared the the open downpipe I was running on for the last 1000 miles or so.

Anyway as for test fitting it, yes we fitted each piece as we went, and used boxes to hold them up.
It ended up coming out very slightly different than our test fit, but it still looks good. On the test fit it was perfectly centered and hanging about a half inch below the tow loop.
Once we got it on though it hangs a little lower and points slightly out to the side, but I still like it, and if I get really picky I can cut it sometime and re-weld it in a better position.

Anyway I took a video, anyone know where I can host it?
 
#9 ·
Heres the video on putfile: Click here to watch SR20DET_exhaust
If anyone can provide a better host though it would be nice (I actually have lots of 240 vids, although my car is a bit ghetto looking)

It sounds a bit better in person.

Anyone know if I will still be able to hear the turbo whirble? I havnt driven it on the street yet (need to go to e-check and get some tags).
 
#18 ·
No its not stainless, thats why it was cheap.
I got em from Jegs, and they have SS pipes but they are like 3X the price.
I am just gonna paint it all black with high temp paint tomarrow or something and that should keep it from rusting mostly.

Im going to a shop soon to change my front tires so I'll try and get a pic of it underneath.
 
#22 ·
Yeah I have a few friends that work at shops anyway but this was as close to free labor as you can get. $25 for welding, and I got dinner for two of my friends.

I actually checked around at exhaust shops, and none of them would do mandrel bent piping (a few didnt even know what it was), and most of them could only do 2.5" max crush bent, and they still wanted $300 to $400.
 
#24 ·
Nice job...I'm thinking of making my own downpipe and strait pipe now.
Was this the U-bend you bought?
Mandrel U-Bend - Aluminized
Tube OD: 3''
Radius (R): 5''
A: 12''
C: 7''
Part#:289-42323
By Hooker Headers/Dynomax? (19.00each)
 
#25 ·
a while back i was thining about welding up my own cat back. but i decided to just buy an $248 (shipped) SSA cat back. its stainless with resinator, muffler and a free test pipe. if you alreaty spent $200 on it why not just buy an SSA exhaust and skip all the fitting and bull.

o yea when you go test pipe i would expect you to shoot some balls of fire out the tail pipe.