30cm x 30cm x 30cm=27 litres
30cm x 30cm x 40cm=36 litres
25cm x 35cm x 35cm=30 ltires
u get the idea? ur recommended size is 24litres to 50 litres. use something in 30 litires, as shown above, select demensions according to ur trunk size/requirments,
this is sealed box, will give u lesser output, but slightly more detailed. if u want higher SPL, look into ported box, i will also see if u can find exact dimensions for that