We have duel plug covers on our hemi no one makes them in cast alum... you will have to use the ones you have or settel on mag. covers wich are more trouble then their worth....they tarnish/corode over night
best luck we have had so far is have them polished then cleared over that will get ya 6months-year IF.. Dont get a scratch in them

1970 barracuda convert. 1 of 59
1970 pro street A.A.R. clone (panther pink)
1971 charger
2015 hellcat challenger. Redline red
2014 quad cab 4x4 ram 8 speed hemi