Notes:
The Windows Registry only has the "explorer.exe" and not the "iexplore.exe" key by default (both Windows 7 and Windows 8/8.1).
Keep in mnd that setting those values may exceed the HTTP RFC specs. Increasing the number of concurrent connections much over 10 may cause problems with some websites not completely loading, or dropping/retransmitting some requests. If you experience problems, just reduce the numbers to a lower value, or return the settings to the Windows defaults.