Which subwoofer enclosure is good - a bigger sealed or smaller vented ?

how much diff would it make in the spl ?? i have 1200 rms of 2 subs together powerd by two mono 600 rms amps eachh..but my sub enclosure turned out to be too big for my trunk..i went to my car audio dealer one guy said sealed would be better option for my trunk and the other guy said vented would be gud..im confused noww..which one you think i should buy ?? i want both gud spl and sq in smaller space..trunk is'nt that big sadly :(