It won't cause a problem.
It's just that it'll take longer to fully charge the bigger battery, so once the battery gets to a similar state of charge to the original, if the car is infrequently used yet the car has a constant drain when not in use then the alternator when the car is used will only charge up the bigger capacity battery to the same state of charge as the lower capacity battery.
HA! you say. I can charge it up when not in use! In which case what is the point of paying more for a bigger battery when you could have charged up the original spec battery when not in use.
The problem with these cars are not the batteries or the alternators, it's the car electrics sucking the life out of the battery when not in use.
I had a Volvo that was able to sit unattended for 3+months with no detrimental effect on it's battery serviceability.
There is no point upspeccing the battery they shouldn't be facing such continuous drain when the car is parked up.
