Blow Off Valves?

[JCL]

Originally Posted by X5X

As for the blow-off valves, I'm not looking for one to achieve that cheesy whoosh sound, I'm not a Honda kid I'm more interested in the performance, and I've heard some good feedback from other BMW forums.

I can imagine two performance impacts. The first is if you end up confusing the engine electronics because of the DME not accounting for the air that was released, and thus reducing performance. The second is with big turbochargers and wanting to maintain transient response after lifting the throttle (race cars). I can't imagine that mattering with the multiple, staged, turbochargers BMW is using to improve throttle response.

There is a potential non-performance benefit associated with replacing a weaker component on the vehicle with a more robust aftermarket valve. That is a durabilty issue, not a performance issue. Wouldn't think that changing out new parts during the warranty period (thus giving up the benefit of your warranty on the impacted parts) would be much of a benefit.