Seriously the problem is with your driving style buddy! Climbing uphill with AC ON and the RPM under 1000 in 2nd gear , you have to downshift to avoid that lag!
I would suggest not to spend of mods like flywheel etc. At the most go for some aftermarket filter and FFE. It won't make much of a difference but you'll feel good. Stiffen up the suspension (check my i10 thread). It will do wonders. Good handling is as important as good power if you want to enjoy driving.