do I need aftermarket heads for blower application?
I am a bit confused because there will be a boosted fuel/air combo. I think gm heads will be ok with that ?
am I right?

If you want to make more hp you have to change heads or spend a lot of money porting your GM heads.

JimV : we dont have flowbench etc here.and porting is very expensive in states.as you told buying aftermarket is the best solution
thnx

Just my opinion but I think it depends on how much HP you are trying to get. There are quite a few blower motors out there running with stock port heads. A blower is not a critical on head porting as a NA motor depending on how much HP you are trying to squeeze out of it. With that said a blower motor will make more HP with a great set of heads over a good set of heads everything else being equal no argument there. Look at how much a 500HP with a whipple will make with NO PORTING as an example. Just depends on how much HP you are looking for then you can plan the rest of you motor build sheet.