NB Miata budget turbo build: $3,500 target, mostly junkyard and Facebook Marketplace parts. Here's my spreadsheet – what am I missing?

I’m Chris, 29, living in a rented house with a 1.5‑car garage that’s already half‑filled with my wife’s pottery supplies. My daily is a rusty Ford Ranger, but my weekend therapy is a 2000 NB Miata – Twilight Blue, 5‑speed, Torsen diff, 130k miles, bone‑stock except for some Flyin’ Miata sway bars and sticky tires. I’ve owned it for three years, done the timing belt, water pump, clutch, and a full suspension refresh. But I’ve been itching for more power ever since I rode in a friend’s turbo NA. The problem? I’m not made of money, and I refuse to spend $5,000 on a “budget” kit from a well‑known vendor.

So I set a goal: build a reliable, street‑drivable turbo setup that makes 200‑220 wheel horsepower, with a total spend of $3,500 or less. That number includes everything – not just the big parts, but fluids, fittings, gaskets, hardware, and even the cost of having a shop weld the oil drain bung if I can’t find a local Miata owner with a TIG. I’m willing to trade my time and sweat for cash.

I started sourcing parts two months ago. Here’s my current spreadsheet (I’ll paste the text version below; the actual Google Sheet is linked in my signature). Everything is color‑coded: green = bought and in hand, yellow = pending transaction, red = still need to buy.

SPREADSHEET – THE BUDGET TURBO NB (as of today)

TOTAL SO FAR (bought + pending): ~$2,485
**REMAINING BUDGET:** $1,015 (to cover tuning, welding, and all the “little stuff”)

The big picture:

• Power goal: 200‑220 whp at 8‑10 psi on 91 octane (California gas). The TD04 will spool fast, which I want for autocross and canyon roads.

• Engine health: Stock internals, fresh timing belt/water pump (done 5k miles ago). I know the VVT needs proper tuning, and the MS3 Pro handles that.

• Fuel: Stock fuel rail, but with RX‑8 425cc injectors (which are drop‑in with adapter clips) and the Walbro 255. I’ll run return‑style using the OEM FPR? Actually I’m adding an adjustable regulator with a return line – the NB has a returnless system from factory, so I need to convert. I’m planning to run a new return line back to the tank – haven’t figured out the fitting at the tank yet. That’s a red flag.

My main concerns – and where I need your wisdom:

1. Oil return – the classic Miata turbo killer.
I know the oil drain needs to be as straight and short as possible, with a 1/2” ID hose, and it must drain above the oil level in the pan. I’m planning to weld a bung on the passenger side of the oil pan, at a 45° angle, about 2” above the oil pan rail. But I have no welding skills – I’ll pay a shop. Is there a preferred location that avoids the steering rack and sway bar? I’ve seen some guys drill and tap the pan without welding – but that’s risky. Should I just use a return pump? (No, too expensive.)

2. Intercooler piping routing – tight NB engine bay.
The Saab intercooler is 18” wide, which means it’ll sit behind the bumper but I need to trim the bumper support – or mount it vertically. I’m leaning toward a “side‑feed” configuration, with the hot pipe going to the passenger side and cold pipe to the driver side. But the NB has the intake manifold on the driver side, and the throttle body points down – I need a 90° elbow that clears the alternator. Anyone have a photo of their piping layout for a similar setup? I might need extra couplers.

3. ECU – I got a great deal on the MS3 Pro, but I’ve never tuned.

I plan to run the base map just to start the car, then trailer it to a dyno shop (the $300 budget). But I need to set up the VVT and the wideband correctly – I’m comfortable with the wiring (I’ve soldered before), but I don’t want to fry the ECU. Does anyone have a good startup guide for the NB VVT on MS3? I’ve read the DIYAutoTune manuals, but real‑world tips are gold.

4. Fuel return – how to plumb it on an NB?
The stock fuel pump hanger has only a feed and a vent – no return port. I need to either modify the hanger to add a return fitting (drill and epoxy a -6AN bulkhead) or use an aftermarket fuel rail with a built‑in regulator and return. I’m hoping to avoid dropping the tank if I can. I saw a hack using the vent line as a return – but that might cause fuel starvation. What’s the simplest, safe method for under $50?

5. Clutch – will the Exedy Stage 1 hold 220wtq?
The Exedy Stage 1 is rated for 215 ft‑lbs at the crank – that’s borderline. Many people run it at 200whp and it holds for a while, but if I ever turn up the boost, it’ll slip. Should I have gone with the Stage 2? I already bought it – I could resell it. Thoughts?

**6. Wastegate boost control – the TD04 internal gate is set to about 7 psi from factory. I want 10 psi – can I just use a manual boost controller (bleed or ball‑spring), or should I use the MS3’s closed‑loop boost control with a MAC solenoid? I have a spare solenoid – but that adds complexity. I’d rather keep it simple for now. But I’ve heard the TD04 wastegate can creep – how bad is it on a Miata?

7. Cooling – do I need an upgraded radiator?
I have the stock NB radiator (plastic end tanks, but it’s relatively new). I’m only going 8 psi – and I’ll install a coolant reroute? I don’t have the budget for a Koyo or CSF. Should I at least add a high‑flow water pump? Or just run water wetter and cross my fingers?

8. The little gremlins – gaskets, studs, and nuts.
I’ve seen so many builds stall because someone forgot the turbo inlet gasket, or the manifold studs are too short, or the oil feed restrictor is wrong. I’ve listed a few, but what specific odd‑ball fittings did you need? For example, the banjo bolt for the oil feed on the TD04 – I think it’s M10x1.0, but I’m not sure. And the coolant line fittings – I plan to tee into the heater core lines – is that a bad idea? Should I tap the water pump neck?

9. Exhaust – the downpipe I bought is generic and might hit the steering shaft.
I know the NB steering shaft is on the driver side, and the downpipe from the turbo (which sits on the driver side of the engine) needs to clear it. The manifold I have is a log that positions the turbo roughly where the stock exhaust manifold was – maybe slightly forward. I’ll need to cut and clock the downpipe. Any tricks for mocking up without a welder? I was thinking of using band clamps and a saw – but I might just pay a muffler shop to do a short section.

10. Overall – am I insane?
My timeline is 3 months – I have a spare car, so the Miata can be down. But I have a full‑time job and a 1‑year‑old, so I get maybe 6‑8 hours per weekend. Is this realistic? What’s the single biggest time‑suck in your experience? For me, it’s the wiring – but I’m prepared to spend a week just on the MS3 install and I/O.

I’m attaching a photo of my spreadsheet screenshot and a picture of the shell under a tarp (yes, the garage is that messy).

What I’m asking from you:

• Scan my parts list – what’s the one thing I didn’t budget for that will cost me $100 unexpectedly? (I’m guessing it’s a new clutch slave or a heater hose adapter.)

• Share your own NB turbo build thread – especially if you used a similar “junkyard parts bin” approach.

• If you have a spare TD04 oil drain flange or a 90° silicone elbow laying around, I’ll pay shipping.

• Most importantly: talk me out of – or into – this madness. I need a reality check.

I’ll document every step with photos and videos, so even if this fails, it’ll be a cautionary tale for the next guy. But I’d rather it be a success story.