I felt quite the opposite when I drove the Abarath, that car doesn't do any justice to its badge and it's a quite uninvolving and doesn't feel that powerful or driver oriented. With a remap,maybe!Thank goodness you didn't buy it, please stick to the GT Tsi or if you Wanna sample a different breed try the Figo.
If you wanna upgrade the head unit then stick with OEM head units like the RCD510 or RNS 510 or the newer ones like the MIB2 which supports CarPlay or get a Dynavin Head unit if you want the best of all.
Remapping will not affect the warranty until the dealer goes snooping around to check the logs the ecu has created every time they have flashed it. With a Vento TDI 1.6 Manual you can push around 130-140 bhp with just a map and if you upgrade it to a GT177 Turbo you are looking at around 150-155 BHP max but it all depends on what you want and your driving style.
The DSG version of the vento has limitations as the box has torque limitiations and you cannot push much.
I know a couple of contacts who can remap the car in Bangalore.