Thanks for responding.
Yes, 4bytes for a transfer rate makes sense to a space at a time. I am more concerned about the TLPs (Transaction Layer Packets). I believe the bus_driver is responsible for creating those TLPs, which are sent off to the Root Complex for the PCIe system. At some point, which I'm not aware of how it does it, the bus_driver decides how much data should be put into a single TLP. That TLP can have numerous different sizes, beyond 4 bytes. I need to be able to create a TLP of size 1/3 KB. I believe that this will require me to re-write the bus_driver and recompile my kernel.