Without going too much into it - a bigger / higher powered battery wont hurt a bit. It will actually serve you better, particularly if you have aftermarket items such as: alarm, stereo, amp, sub, central locks, gauges etc. Anything electrical basically. You will have a lot of trouble killing your new battery.
I replaced my battery a few months back and I upgraded to a 580 cca one based on the amount of stuff Im running [just about all above mentioned].
The specs are in the manual: stock capcity is 340 cca's and the alternator is whats rated @ 80 Amp. on the 2.4!
Crown Casino? Thats in Melbourne Mitza! Are you coming down to see "what its all about"
[j/k].