You might want to look at Still Static, you can get seriously low drops but still have the handling you need for added power.
Your question shouldn't be "which should I do, power or prowess" but more "which should I do first?".
A bit of patience, part hunting and being prepared to pick up a spanner to crack the simpler jobs yourself will result in a more modified car than your budget first allows.
I really love your original Up!, it looked amazing.