Tried this but didn't see any change. I have Verizon DSL in NYC rated at 3 Mbps download and it typically tests at 2.6 - 2.7 Mbps actual. Stayed the same.
The Windows notes on this parameter say the following: "Important: If a bandwidth limit is set for a particular network adapter in the registry, this setting is ignored when configuring that network adapter." Maybe that's why no change?