If you fz150 user any 250 cc is pretty plentiful actually.

It's fast and more importantly manageable handling.

Faster bike means bigger bike. Bigger bike means harder to handle. It also mean more dangerous for you and makes you slower.

My suggestion is go for 250 cc less
As this type is city friendly and you still can outrun those modi kapchai

For low seat height and more power, I think there's really just Honda Rebel.

Annual insurance 600~700 (2~3x than FZ150i)
Roadtax RM180 (RM2 for FZ150i)
Tyre 600 every 8k~12k

I understand, plus you need to spend 1.5k and time for B Full license. As for z650, i never ride it, so i cannot give exact opinions but i got test ride Ninja 650, same engine. I feel like the engine a bit jerky, not smooth. That might be just my opinion only.

For 25k, i suggests to get new 250cc bike compared to second hand 650cc. Not worth the hassle of repairing. The cost will add up really fast. For example, if the bike you buy is using old tyres or chain, that is around rm 600 that you have to spend soon after.

i'm looking for bike that can outrun crazy car drivers in the morning....modi kapchai is a plus tho 

i plan to take used r25 and modi r3 ... howsit? 

250cc is pretty much can do all that.

R25 seem ok but i never used one. So no comment.
Z250 is pretty fast. Not sure about duke 200 or ns 200.

But last week on my way to work. This duke pass me super fast and he keep speeding. But the z250 pretty much keep up with it easily. If you can get used duke. I think its a bargain tho. It's pretty cheap.