BIG TURBO

So today I drove 4 hours to St. Louis for this amazing deal on a g25-660 for only 2k,I didn’t realize he would include all of this other stuff,a wmi pump,horns,spacers,wing riser kit,and a sound symposer delete,I have a few questions,is there anything else I need for the wmi?Not trying to sound dumb but are the horns for honking or do they actually have something to do with performance?and is isc a good brand,thank you for reading