Police has nothing to do with your grades,whether you are through out position holder or 2nd div pass you are equal. However it will help you in final merit & Selection.
4 batches of approximately 1000 Sub inspectors have gone through this stage and they survived in this pay and 5th batch haven't joined yet.If you want more salary go to private sector,if you consider your self competent enough try your luck in PMS ,CSS. Police has Charm but not salaries.And of course you get paid in training period.
Final advice for you is ,If you have time and resources go for something else like FPSC jobs, being federal they have better privileges than Punjab govt