[911st]

Flames can be good. Can be hard on the turbo and the muffler. Can turn the turbo into a turbine which can have some anti lag benefit on a race car.

FWIW, Pat's is a good example. It keeps the air to fuel ratio better balanced between shifts by bleeding back to the turbo intake tube side. This is how the factory 930's work in principle.

The inexpensive bosh black plastic BOV like on the C2 turbos and that Pat has above works well. Forged aftermarket one's are easy to find and can flow more.

Better than both setups is one that is plumbed like Pat's but is a special style of BOV that stays open at idle and cruse, not just with throttle lift. It allows the turbo to spin a bit faster untill acceleration is called for as it bypasses extra air around the turbo.

It then closes with acceleration for faster boost response with acceleration. On my C2T this strategy made a noticeable lag difference.