My Yaris accelerate too slow !!! any suggestions ??

[Jack Yak]

I have 07 yaris sedan ... 1.3 A/T

previously ,, the top speed was about 180 km/h

then i changed the wheels from 180/60/ R 15 to 195/50/ R 16

with HRS sport rims

then i noticed that i couldn't accelerate to 180 km/h anymore !!?

the car could hardly exceed 160 km/h !! ??

i did some modifications to improve the acceleration/top speed

short ram intake (K&N)

jasma cat back exhaust .. 2" inches tubes

i feel some improvement ... but the top speed still sucks !!

i'm still looking for faster acceleration and increasing the top speed a little bit !!

Any suggestions ??

<<<< that's video showing the acceleration from 90:150 km/h

http://www.youtube.com/watch?v=NAZLVNqzNy4