Question about heads and setups and differences

Just got a question...Well my question is GT40Ps versus me getting a cheap aluminum head. If i got the gt40ps i would get them from tristate so they run about 600 bucks...If i got an aluminum it would run me about 800-1000...

Keep in mind im a college kid and money is hard to get and stuff.

Now i am going to be putting my nitrous up to a 125 shot on my car when I do heads and cam in the spring along with 30lb injectors and bigger fuel pump...blah blah blah

So when going to the track is there going to be that big of a difference if i go with the Ps or the aluminum heads? The main thing I want is to be somewhere in the 12s at least. I will also want to compete with my friends cars since one plans on getting a 2003-04 GT and supercharging it and the other is getting a 2005+ and supercharging it.
 
from what i understand on the GT40p heads, is that they will flow a good amount. but they have to have a good deal of port work done to them. i don't have experience with them, maybe some one who has will chime in. but also with the aluminum heads you save a good amount of weight. you also have to factor the extra port work to the GT40 heads above what they cost you.
maybe you could look into a set of used aluminum heads?