How fast you run in the 1/4 depends on more than just how much horsepower you're making. Since we're talking modified cars here you have to worry about things like what kind of clutch, what kind of tires, any sort of added traction bars, etc.

That said, you may indeed be able to hit high 13s with the GReddy turbo (keep in mind that you don't get to keep your i/h/e when you put on a turbo) but it's really speculative at this point.

If you're looking at the FMIC GReddy kit that means you don't care about CARB exemptions so I would look into another kit which makes more power if you're really trying to bust some low ETs. The GReddy kit is more aimed at providing a responsive engine for driving on the street because it has a smaller turbo that spools up more quickly than the ones that come in kits like DRAG and RevHard.