Why not just use Nitrious?
 

I want to run high 12s low 13s. Why should I get heads and a cam when I could just spray?

Cuz, with heads and a cam, it won't hurt your bottom end. You will get a lot more life out of your engine and you will have that horsepower whenever you want. Do the heads and cam, run your high 12, then spray into the 11's!!!:cool:

If reliability is a factor....spraying is a little more dangerous. If you have high miles, it might not be a good idea. On a stock motor I wouldn't spray more than 125. I just bought a NX kit adjustable from 35-150, for $500. The purge kit was $100. After buying wire, connectors, steel pipe for the purge, colder plugs and other misc. crap, that's another $50. But I've got it at 100-shot now, and its a rush! I am also going to get a new fuel pump, and new plug wires. If I had the choice to make again, I'd still go with the nitrous......although later on heads and a cam couldn't hurt......

I would think a heads/cam combo with the right suspension and tuning will hit mid or sometimes low 12s (Smokin something here has a 12.3 on stock heads....)

People like different ways of making power...I rather go na and have the power on hand rather then hitting a button and risk damage to my engine...but if you know what your doing you should be fine