Hey just my 2cents, if it's after 3000rpm when she's on boost maybe that's enough to cause a leak in your exhaust system before your oxygen sensor. Giving you that lean reading. I'd guess if it's on the intake side you'd loose boost. And run rich. If anyone knows a shop that has a smoke tester, it's an awesome tool for finding any intake related vacuum leaks for one. Could also be used to check your exhaust and engine for leaks. Hope you get it sorted soon.

using the Perth-WRX mobile app

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