When you get a turbo you get rid of the stock intake and header. The turbo manifold, turbo and downpipe replace the stock exhaust manifold; the charge pipes replace the intake.

For now I would just make sure that every little bit of maintenance is taken care of. From there get some good tires (I see now that you have them), refresh the brakes and then tune the suspension a bit. The car will go the same speed in a straight line but will be much more satisfying to drive.

But hey, that's just me and maybe you really want to put a hurting on some mullet-wearing Mustang drivers and I'm not one to stop you notwithstanding my negative opinion of street racing in general.