how much power will a 12A make with basic mods like street porting, exhaust, bigger carby, decent flywheel, i have herd that doing this will give me about 150 hp is this right

There's no limit...You can get about 200-250 on n/a 12A. There's a lot of set-ups that you can try. Street port, bridge port, etc. If you do pheripheral port you can get a lot of power. Here in Puerto Rico are a few cars running high 9's with 12A pheripheral port power plants, some of them have 450-480hp with nitrous.

I heard from racingbeat that you can make aroung 280WHP with a 12A. Thats with basicly everything done to it (Like a big PP port), and I think they said they were running a modifyed 52mm weber IDA???