First, EXCELLENT that you had your boy neutered!!! I think he might calm down a bit once the hormones are gone. But, Piko just might be a bit spoiled! Keep us posted on his behaviour.
PS: Tell Piko that it is for his good that he is being kept inside. It is much safer than being outside and you are doing this because you love him and want him to be with you for a long time!! Are there windows that he can look out? Can you place bird feeders where Piko can see them? And be sure to give him quality and play time! Good luck!!!