i dont think 4 in a trunk is a good idea no space and it wont sound that good in your trunk i dont think i have a friend who has a s-10 and he had 2 nice audiobahns then he sold it and got 4 mtx 4000's and they dont even compare anything over 2 isnt necessary especially 15's unless you go to like 6 subs i cant see a big difference worth the money to me.