I have noticed that the initial congestion window in my traces is 8920bytes~=6*1448. rfc3390 states the initial cwand should be max 4000 bytes(around 3*1448).
At first i thought it might be because i'm running my server on mac os x, so apple might have modified the tcp stack. Therefore I tried running the server on a Linux box (2.6.38) however i'm getting similar results 13032bytes=9*1448. Both server and client machines are running on a local network (via a router). Any ideas why the initial cwand is so large?