We have a Siemens LF97BB532 with a Naber Compairflow and a large flat duct. At the highest setting, despite the high installation position (otherwise I almost always hit my head at nearly 2m), it extracts really well when searing. However, this then requires an open window, the negative pressure is heavy. This is probably also the case with downdrafts. The hood is also nicely quiet, it depends on the proper air exhaust. No flexible hoses and cross-sectional reductions, and then a good wall box!