Used Bandwidth on a PCI Bus

[Raghunath Tilak <Tilak@ambernetworks.com>]

Hello,
Is it reasonable to assume that total utilized bandwidth on a 33 MHz, 32
bit PCI
bus is 40% of the peak bandwidth available? ( Only 52.8 MBytes/sec of
total 132 
MBytes/sec is used. The rest is spent in the overheads)

I am trying to estimate the traffic on the PCI bus in our system. I
wanted to know 
at what point I should be concerned about the traffic on the PCI bus. 

I just wanted to know the rule of thumb for this.

Thanks in advance,

Raghu Tilak