Quick question about rear differential
 

What is the standard differential on my 2004S? Is it just simply an open differential? From what I've read you can purchase an aftermarket LSD or PSE or whatever was a factory option that worked kinda like LSD but used computer controlled braking to even slippage. Is that all accurate?

No. The factory diff is an open unit. 2004 cars did not come with traction control, but with stability management (PSM), which is not traction control. PSM kicks in when the car's yaw angle exceeds certain preset limits and brings the car back into a controlled line. When standing still, or moving slowly, there is no measurable yaw angle, so the PSM would remain dormant.

How does the 99 handle this? Mine has traction control and limited slip differential?

Your 99 probably does have traction control, which preceded PSM; but I do not know about the limited slip as I do not believe that was even an option back then.

I do not think Boxsters started coming equipped with an LSD til maybe 2007 I could be wrong. If I was a betting man you have an open diff on the bad boy. My 2001 is open diff, no trac control and no PSM... its just me and the road. sometimes i feel like its me and the road and almost the ditch.