The Great (and stupid) DIY 3" Exhaust Tread
 

Let me first say that I'm fairly certain that I'm going to regret doing this in the long run, but the journey will be entertaining, if nothing else.

My objective: To replace my completely adequate, but somewhat leaky, 2.5", FM-based exhaust system with a (probably horrible, and completely crappy) home-built 3" system.

Purpose: Ostensibly, to achieve 3" exhaust Nirvana. Actually, to have something to do while the cold(er) winter months saps the life from my ever-aging body.

The Plan: Create a masterpiece of design, engineering and good old American know-how (but actually to cease asphyxiating myself when I have to drive with the windows up to avoid freezing to death because I've borked the heater vents the last time I had the dash out).

Right now, all I have is a glimmer in my eye, a shitbox HF welder and a few bits and pieces. Now, before you start with the "DUDE! Get a REAL welder!" comments; a) I don't have spare cash flowing out my ass, and b) I want to make this a difficult as possible on myself because "I'm that guy".

What "bits" do I have now? Just a China-made T25 outlet to 3" V-band adapter (see previous comment about the HF welder for reference), and a 90-degree 3" downpipe from Himni Racing. That's it. That's as far as I've gotten.

Next step, put the car up on a lift and figure out what shapes and lengths of tubing that I'll need, then order twice as much from Columbia River as I think I'll need because there will be MUCH wastage.

For now, it's just a pipe dream...yeah, pun intended.

Buy a used MIG off of facespace and save yourself the headache........as well as a useful measuring device

You will thank us later

I will take this under advisement. The search begins...

Yeah flux core sucks. I know you said you didn't want to hear it but you need a better machine. The orange or green units from HF aren't that terrible.

I use a Hobart 140 mig machine. It works well enough.

I know, I know! Punish me for my sins!! I REALLY want a mig machine (I really DO), but for now I'm stuck with my POS flux core HF boat anchor. I've gone so far as to do the AC to DC "conversion" on it - you know, big ass caps, a rectifier and re-wired it for DCEN. I know it's a POS, but right now I'm cash-limited so treat this as a "science experiment". I'm going to buy some sacrificial stock to practice on. I've been doing some practicing on thin, flat mild steel already - I'm not good (yet) but I'm improving using inferior tools.

If I hit the lotto - not a good bet, 'cause I don't do that - then I'll get something better to work with. Or, if something pops up for a good enough price, then I'll splurge. Until then...

"To infinity, and beyond!"
https://cimg2.ibsrv.net/gimg/www.mia...ebabd34152.jpg

I cobbled together my first 3" exhaust, first time doing something similar too. Only slightly banged off shit when the hose clamps fell off the hangers. Might still be a list of bends I ordered from summit in my thread somewhere.

https://www.lowes.com/pd/KD-Tools-Ex...Cut/1000972618

One of those things is super clutch, but you gotta be using steel and not stainless. Can also find them online a lot cheaper.

Godspeed my man. I (very stupidly) built a custom 3" exhaust for my NA this summer. I like to punish myself, so I did it all with Flux core wire and a cheap MIG/Stick machine from Amazon. Used mild steel all the way, and ceramic coated it in the end. Not the prettiest thing, but it gets the job done. I might still have the parts list lying around somewhere...

I'm not sure what type of muffler you're running, but the classic Dynomax Race Bullet 'Resonator' paired with a straight-through Magnaflow 5x11x22 Muffler suited me well.

Just remember to add flanges so you can take down a section or two at a time. Installing one complete huge exhaust all at once sucks. Ask me how I know..

Just get on OfferUp and Craigslist and keep your eyes peeled for a Lincoln or Hobart 140 mig or a HF Titanium or Vulcan mig. Welding with gas is so much better than smoky flux core that turns out like hammered dog shit most the time anyways. And you'll be able to build it out of stainless like God intended. The welder will pay for itself eventually. Also dump your HF one on OfferUp and get a little money back.

The gods have spoken. I repent of my flux core ways. CL, here I come.

I definitely was going to use mild steel. No way was I going to try this with SS, knowing that there would be many mistakes made. And it will definitely be ceramic coated once done.

My existing muffler will go to the scrap heap. It's 2.5" in/out, so no bueno. Thanks for the resonator suggestion, that was going to be a question for the community. And a nice Magnaflow is in the plan.

Also, this will be done in sections with a midpipe so I can swap in my existing FM cat when it comes time for the annual GA emissions check.

I picked up some practice stock today so "welding class" will resume this weekend. If I get something that looks better than dry boogers on a desert wasteland, I'll post pictures.

Otherwise, the search for a decent rig commences.

If your POS HF welder is like mine, you’re a tank of gas, a $20 Amazon regulator and a roll of decent wire away from running MIG. I converted mine and get very okay results. Plus you’ll need that stuff anyway even if you get a new welder so you really have nothing to lose. If you have money to burn, spend it on a good helmet instead- the HF ones are hot trash and you’ll suck even with a good machine if you can’t see what you’re doing. There are some tricks to get around the lack of voltage adjustment; if you want it cooler, move the ground further away. I’m in ATL and we’ve met at the track, if you want to come check out my setup just let me know.

There's an even cheaper one that is flux only. I'm guessing he has that one.

Seconded on the helmet but if he doesn't have enough money to get a MIG machine then I don't know if he can get a decent helmet either. Maybe just go with a fixed shade one. I've got a Viking 3350 and it's pretty good. The older model that doesn't have 4C tech.

Gonna be that asshole who goes againsy the current. You can 100% do this job with a DCEN converted $80 HF flux core. We did my friend's downpipe with his still running AC. It's ugly, but it works. You are going to have to chip a lit of slag, grind out a lot of welds, and fill a lot of holes though.

If you are blowing through, you can switch to doing a series of tacks instead of trying to run a bead. Also, a piece of copper pipe smashed flat is going to be your friend, you can use it for backing while filling holes, the weld won't stick to the copper.

That said, I went and got myself a $100 Pocket Turbo mig (it's the same as the 120v one snapon sold in the 80s and 90s) off facebook and then a tank of gas. It's way, way better.

I'd be down to take a look at your setup - what plans do you have this weekend? PM me.

Yeah, I've got the bargain-basement one. Bought it about 5 years ago and it sat in the box until last month. And you guessed it, I got the HF helmet as well. My only redeeming quality in all of this is that I didn't know what I was doing at the time, and I just got what I saw, without consultation. Not an excuse, and explanation - mea culpa.

I'm all for being "contrarian"! I know all about the slag, and the BB's, and the smoke, and the grinding, and the blow-throughs - it doesn't take too much time to figure that out real fast. Like I said, I'll be practicing until I can come up on a better rig.

I've been known to do things the hard way, and the wrong way, using inferior equipment. Been doing that for a long time now.

Just some initial bits I've acquired; T25 to 3 in vband adapter (from Himni racing) and a generic EBay 3-in 90* downpipe. These will be the starting point.
https://cimg7.ibsrv.net/gimg/www.mia...e63279eab2.jpg
https://cimg8.ibsrv.net/gimg/www.mia...7b2a2683e1.jpg
https://cimg9.ibsrv.net/gimg/www.mia...82f98f0073.jpg

You're gonna have to cut the shelf with that.