I always think that if you face a sub directly out towards the boot then its facing away from you and so will sound worse.
If you face it towards the rear seats then it will sound cack.
So which is the best direction? How about facing them upwards as this is the most logical to me. I was thinking of taking out the parcel shelf and bulding a box that holds both subs and 6x9s facing upwards. Is this a good idear or not? Has any1 done this?