[msej449]

Sorry, I can't help with the ZF specialist question as I'm based in the UK. All I recall from other threads is that people have had to contact ZF country HQ directly to find their nearest specialist.

Re the whole charge pipe thing. One thing that's emerging is that in 2019 BMW brought out an uprated charge pipe as a replacement. And that independents that prefer to use OE parts (something that's usually reassuring) will stonewall over using non-OE parts like the VRSF. There's also an implication that the uprated OE part is good enough for a stock car and that the metal pipes are more designed for boosted engines i.e. over-engineered for a stock engine. But this isn't necessarily definite. And as a guideline cost, here in the UK, my local independent quoted GBP £497 ($668) all-in, including labor, BMW OE uprated part ($363) and tax.