These are brand new cylinder heads for 2005 to 2010 mustangs with 3v cylinder heads they have been ported from 175cc stock to 195cc then the steal valve guides were removed and it was ported again so no sharp edges remain then Bronze valve guides were installed with taperd ends for better flow with new Vinton valve seals were installed then Trick Flow stainless steel valves were installed then Manley Nex Tek valve springs were installed with Comp Cams valve retainers topped off with MMR valve locks. These heads should give you 80hp to 100hp over stock heads and up to 200hp with performance camshafts