[speedshopmike]

some of the many many examples of domestics without bov's include the syclone/typhoon, svo mustang, turbo coupe, merkur, all the dodge products using 2.2/2.5's, the 1.8 turbo gm sohc cars, 2nd-gen turbo trans am, 3rd gen turbo trans ams, etc.
not arguing their usefulness, just their necessity on mild turbo applications.
to this day, even on low-boost Vortech/similiar centrifugal blower kits, a BOV is not included.
it is part of higher boost kits and kit upgrades to high-boost.
on maf vehicles, the recirculating bov's create driveability issues when not oem-engineered due to maf backflow.
when i changed my procharged mustang to externally vented double bov's the driveability went from unacceptable to almost oem-like, as an example.
a new company, abaco, has released a brilliant digital maf that can be digitally filtered to ignore backflow, among other neat features.

compressor surge simply isn't a critical issue on small, responsive turbos set for low boost with typical oem short intake tracts.
any serious turbo effort should incorporate them.
any serious centrifugal effort should use as many, as large as possible, units as possible.
lastly, euro cars gravitated toward them because they, regardless of turbo app, reduce lag between part-throttle shifts.
auto trans vehicles don't have this particular issue.