subframe bushing: poly or aluminium?

[formulafr]

hi all,
i don't know if it's the right place for my question.

1- i'm about to replace my old rubber bushing by solid ones. i also have poly ones. should i put the poly or should i go with solid, my firebird is a street car but i like taking hard corner. I'm planing to use sub frame connector next.

2- solid aluminium bushing seems to be higher than stock, must i machine them? to what final size?