So I just got myself a 2007 Yaris...

[why?]

pulleys do help the car accelerate faster by a tad, they make the car overall feel lighter. lightweight wheels help a lot too. And if you really want faster revs, a lightweight flywheel to top it off.

And of course for more power there are all the usual bolt ons.

If you do mean the delay when you hit the gas and the car accelerates, that is the drive by wire lag. Pain in the neck. There are boosters if you really want to buy one, they basically make the car accelerate a bit faster and remove the lag. Sprint sells one, Blitz sells a more complicated one with a ton of different levels from eco to sport.