Looking for technical input from anyone I’ve been chasing this for a while and I’m pretty exhausted.

Car is a 2019 PP MT. The car used to run well but for a long time now has had severe power loss — honestly feels down \~100 hp. Boost comes on late, pull is very weak, and the car feels like it has constant drag or resistance.

Some symptoms are long turbo flutter on lift, rich pops/backfires, oscillating intake sounds, and what feels like aggressive ECU torque/timing intervention. Behavior is consistent hot and cold. Seems to be getting worse over the last few months.

Ive gone ahead and removed the JB4 and reset fuel trims. Upgraded HPFP to sonata pump. Had Fuel pressure and injectors verified by Hyundai. Wastegate arm checked and is solid. Crankcase, intake, and charge system smoke tested — no leaks found. No CELs.

Was suspecting diverter valve issues but the dv has been replaced with a GFB bpv and issues still there.

Kinda at a loss right now tbh. Been trying to track this down for two months, hyundai and another shop were unable to find the problem.

Mods

Forge intake/forge inlet

Maintec catless downpipe

Borla exhaust

Sonata HPFP

Csf intercooler

Colder plugs

Update-boost issue. Sound clip