16v – Building the GOAT

Two blocks of Aspirational Horse Power provided by @thomas_and_a_vw

Table of Contents

• Overview
• Bill of Materials
• Build Log
  • 2026-07-12 – Motor Acquired
  • 2026-09-21 – ITB Research
  • 2026-09-30 – ECU Research
  • 2026-09-30 – Fuel Pressure Regulator & Fittings
• Resources
• Notes

Overview

Building a 9A 16v with modern fuel management and individual throttle bodies. The goal is maximizing NA sound while keeping the build relatively simple and the driving experience fun. CIS-E out, EFI + ITBs in.

Bill of Materials

Build Log

2026-07-12 – Motor Acquired

• Picked up the 9A block from @thomas_and_a_vw at Mk1 Madness 2026

2026-09-21 – ITB Research

Haven’t pulled the trigger on throttle bodies yet. Four options on the table, and each one’s pulling me in a different direction:

Jenvey’s the known quantity: it’s the kit most of the 16v crowd actually runs, so fitment and documentation are a non-issue. AT Power is the expensive outlier, but it’s the only one of the four offering drive-by-wire, which would let me skip a cable throttle linkage entirely. OBX is the tempting “just buy it, it’s in stock and cheap” option, but there’s no install guide and I don’t know the brand, so I’d be on my own if something’s off. US Rally Team’s 40mm bore is smaller than the other three, and I’m not sure yet if that’s a meaningful tradeoff for this displacement or just a different philosophy.

Leaning AT Power right now for the drive-by-wire alone, but haven’t convinced myself it’s worth the 2x price and 2-month wait over Jenvey.

2026-09-30 – ECU Research

Started second-guessing the MicroSquirt that’s been sitting in the BOM since the start, so I looked at what else is out there.

First thing that stood out: Link doesn’t publish pricing anywhere, you have to go through a reseller to get a number, which makes it hard to compare apples-to-apples against Haltech’s sticker price. AtomX is the right size for the 9A, but without a published price I can’t tell yet if it actually beats Haltech on cost.

MicroSquirt is still the budget anchor at $380, mostly known for being DIY and community-tuned rather than having polished factory software. Haltech’s Nexus T1 is where I’m leaning mainly because the price is upfront and it’s sized correctly for 4 cylinders, but I haven’t yet decided if the jump from MicroSquirt is worth it or if I’m just paying for nicer software.

2026-09-30 – Fuel Pressure Regulator & Fittings

Looking at Radium Engineering for the FPR and AN fittings: their parts keep showing up as the reference point in other EFI swap builds I’ve read through. Two regulators actually fit this build:

• DMR ($170.95): mounts straight into an 8AN ORB fuel rail port, no extra plumbing. Only works if the fuel rail (whatever comes with the ITB kit) actually has that port.
• FPR-D ($299.95): standalone, universal, and has a built-in fuel pulse damper. That damper matters more here than it would on a stock intake, since ITBs mean each cylinder’s injector pulls from a shorter, less-buffered section of rail, so pressure pulses are more likely to show up as a rough idle or uneven cylinders.

There’s also a DFPR (dual regulator, ~$299.95), but that’s built for staged port+direct-injection setups, not applicable to a single-stage port-injected ITB engine, so that one’s ruled out.

Haven’t picked between DMR and FPR-D yet: it depends on whether the fuel rail that ships with the ITB kit has a port the DMR can thread into, or whether I’ll need the FPR-D’s inline flexibility regardless. Fittings themselves (AN sizes, adapters) also come from Radium’s universal lineup, but those depend on whatever rail/regulator combo wins out, so that’s still open too.

Resources

• Jenvey Throttle Body Kits
• CAE Racing Short Shifters
• Mission Motorwerks – engine machine shop

Notes

• This is a living document. Updates will be added as the build progresses.
• Questions/gotchas: TBD as they emerge.