hi nilesh ,

STPI is calculated on the basis of your performance in ESE (End Semester Examination) of last two semesters i.e., 5th and 6th.

If you perform well in ESE of last two semesters, then automatically it will increase your STPI result.

For example,

Suppose, you have scored 8.0 and 8.5 SPI and your friend have scored 7.5 and 7.9 in last two semesters. You have got good internal marks and your friend have got poor internal marks compare to you. But you have scored less marks in ESE compare to your friend, then your friends STPI will be more than yours.

Conclusion: Focus more on ESE or GTU exam than your internal marks like mid sem or viva marks or project. They will not help you in getting good college, but your STPI will help.

I hope this answer can clear your doubt regarding STPI.
All the best :)