I have an aftermarket MAF cause I thought I was cool getting all these parts when I first got the stang not knowing the stock one was fine until like 350-400 HP. I think this could be a problem with my car if it is calibrated wrong because my car kind of flattens out past 3 grand. My question is can I just unscrew my old MAF and drop it in where the aftermarket one is or do I have to swap the pipe out and everything?

 

If your new maf is bigger than the stock one which I'm sure it is then you'll probably have to just go to your local hardware store and get a couple of rubber reducers to lower the pipe size to fit the stock maf. Your right about the maf though, if the new maf is not calibrated to the size injectors you have it'll make it run bad.

 

It may not be the MAF, it may be the nature of the engine with the restrictive NPI heads on it also.

 

The NPI motors are weaker than the PI motors but it's not going to just quite pulling all together at 3000 rpms either.