The 1.8T 20-valve turbo four (Mk4 GTI era, and shared across a huge swathe of VW/Audi) is a tuning legend — and I've built plenty of them. A strong bottom end and a bottomless aftermarket made it the affordable big-power engine for a generation. It has well-known ownership quirks, though, and the engine code matters because outputs and details vary. See 1.8T Coil Packs Sludge for its signature faults
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