pf queue bandwidth estimation

[niya levi]

using broadbandspeedchecker.co.uk i measured the bandwidth on my virgin
media line,
the download speed varied form as low as 20Mb/sec up to 50Mb/sec
depending on the time of day the test was run,
what will be the result if i put a value for the queue bandwidth which
is greater or lesser the the maximum download speed ?
shadrock