Has anyone swapped thier battery out with another one. Does it start better or does it seem like it has more power. seems like the battery in my car is very weak. I also have a system so i don't know if that has anything to do with it.

There are at least a gizillion threads on the OEM battery and the recommended replacements. Please search for them and read some of them. Also go to the link below for information on upgraded starting components.

http://www.finishlineperformance.com/rx8/docs/pdf/01-004-05-1448e.pdf

thanks