pistons
connecting rods
main and engine bearings
bolts
studs
valve & springs
gaskets
etc.
u get the basic idea
all the milage on ur motor wont matter it may last up to 10 billion miles
depending on how u take care of it of course
its the same things but ur basically puting new ones plus there much stronger
the pistons are at a different compression ratio either for boost or for N/A