Batteri Amp ?

Buying a new battery for one of my VW's and curious about amp size.
If the physical batteri size and has the correct position of poles , then does it matter what size amp it is ?
Things i read is, 35 is ok for standard VW, 50 is better, but if big motor and stereo, then a 65 is best.
Can a over size battery do any harm ? Like the generator ?

Coty

Coty, in Finland EVERYBODY drives with 65amp as standard - with no problems what so ever.:) Actually if you dont use that, your car wont start doing wintertime:)