Having paid 19,012 Rupees in excess baggage charges on a PNQ-BOM-BHO recently this is what 9W allows typically.
if you dont have any status the check in agent is allowed to waive a maximum of 3kg per pax. Rest is a baggage fee. You might check in 23 kgs and carry on the extra 4 kg. I am only aware of a 20 kg / 30 kg (J/ Plat) baggage allowance on domestic sectors for checked baggage.
If you have status or in business class they allow extra 10 kg on domestic sectors.
http://www.jetairways.com/EN/MY/Plan...Allowance.aspx
Ofcourse if you can sweet talk your way they might not charge anything extra.