Getting 150 out of a trunk is no easy feat. Most people I've talked to say port foward, subs foward with the trunk sealed off. Porting through the rear deck may or may not work because it would be kind of hard to fit the ports through the stock 6x9 (or whatever) holes.
If you want a DD/comp setup, you can use aeroports. Make them external and it will be easy to change your ports. Or you could plug one which would lower your tuning. For example, 4 4" aeros tuned 50hz, plug one and it'll bring your tuning down 7-10hz (depending on box size). That's still high tuning, but low enough for me, so it depends on your preference.