What is the best upgrade I can do on my SE K800i to get the most out of it?

[SeaMonkey]

I have seen applications on the forum (SETool 2 Lite, XS++ and FAR) but don’t know what they really do. I guess the first thing I must do is upgrade/change my firmware. Can I upgrade it to K810, K850 or even better? Which application is best for that?

Yes you can convert K800 -> K810 but the tool depend on CID of your phone, so for start just install USB flash drivers and connect phone with XS++ and XS will create log-that log post here without IMEI number and will direct you to wright direction.
Here you have tutorials: USB Flash Driver Installation - Guide - Top Sony Forums
XS++ 3.1 Guide-Flashing, Customizing, Recovering - Top Sony Forums

[xtreme]

install USB flash drivers and connect phone with XS++ and XS will create log-that log post here without IMEI number and will direct you to wright direction.

OK, thanks!

Here is my log:

22:33:49| Baseband ID: 9900

22:33:49| Protocol Version: 3.1

22:33:49| Phone name detected!

22:33:49|

22:33:49| Profiling SEMC phone...

22:33:49| Platform: DB2020

22:33:49| OTP CID: 49

22:33:49| EROM CID: 49

22:33:49| EROM Color: Red

22:33:49| Phone ID: K800

22:33:49| Region: EUROPE_4

22:33:49| CDA: CDA102568/13 R4A

22:33:49| Firmware Version: R1JG001

22:33:49| EROM: R3A011

22:33:49| Ready for operation!


I found in the guide "1) Converting to CID52 (if required)" but can't find anything about if it's good or bad to upgrade, just that I Can't Revert Back To CID49 Or CID 51.