45AH is enough. you can check the original battery by checking the battery compartment. normally it is designed to accomodate original battery. if it came with 60AH battery, the compartment is much larger than 45AH. so when you fix a 45AH, there are some spaces left on sides.
The best battery currenty in the market is Amaron.
if your car came with 60AH battery and now has 45AH, it is better to put 60AH when you replacing 45AH. but for 1600cc petrol engine, 45AH is OK.