well ahmad bhai, once again, mubarakaan for the new beauty u've booked.... Allah Paak naseeb farmaye...!
as for ur modifcation options, shazo bhai has already mentioned good options.
IMO, try to stick with the stock condition of the car at ur level best. Xli looks better as an Xli and not GLi at all.
Just go for power windows and keyless entry. Try to get the remote in altis style, i.e built into the key.
The shop wala will make u two brand new keys for the car. Just keep the original ones at ur home and use the remote ones for use.
XLi has power locks. U'll just need to get ur self one motor in the driver's side door and yer good.
Try to get the original toyota motors from an altis or a GLi, easily availible at chor bazaars these days. Xli is one of the reasons of GLis and Altis being stolen the most.
even, after u save up some money try to hunt for an ABS system from bilal gunj as well... A person I know, got in his Xli for rs 35k only.
In the end, do go for some good tyres on the car like Yokohama advan dB v551, Michlien energy saver, bridgstone MY01 or dunlop direzza...
Try to get rid of those eurostars asap.