My STI will barely engine brake ... granted it's got some inertia, but with an AWD drivetrain and a turbo providing backpressure you'd think it'd slow down, but it's only rocking 8:1 compression, LOL.
Some of that is emissions tuning. Throttle is drive by wire now, just because you lift doesn't mean the throttle is closing.
I hate the way that these new e-throttles respond when you lift - they don't snap shut! They basically... don't. And most of them are slow to respond to a request for power, too.