Neither.
The maximum weight for a Bowling ball is approximately 7.25 kilograms or 7250 grams.
It is measured in kilograms, but it also depends on the actual weight. The average bowling balls you can buy on the market weigh anywhere from 6 lbs to 16 lbs.
kilograms
10 kilograms
grams
825,000
You could (theoretically) use either... However - Kilos is the preferred measurement.
I think it is kilograms
1300 grams
290kg
The weight of a guitar could be determined in either kilograms or grams, but preferably in kilograms.
You would weigh a baseball bat in kilograms.
Grams