This is 2 bulk inserters almost saturating a blue belt, roughly 40 items per second. The second splitter can be replaced with side loading if you have the space.
This is 6x legendary stack inserters fully saturating 2 stacked green belts using just 2 splitters. This is not quite balanced but is close to balanced as inserters 1 and 6 unload only ~20% faster than inserters 3 and 4. Inserters 2 and 5 are in-between.
This setup with bulk inserters will almost saturate an unstacked green belt.
