no do not turn the box around
no you do not face the subs towards the engine unless you have the box in a open cab like a minivan or a navigator or something like that. to remove the rattle you could eithe do 1 of 2 things. both done will work even better.
1- release as much air as possible from the turnk into the car by cutting out airholes in the back deck and the back armrest as well totaling three new airports coming from the trunk into the car. each about 4'' to 6'' wide. the bigger the more bass and less rattle.
2- buy 50 square feet of fatmat and that will be more then enough to sound deaden you trunk and stop the nasty vibration as well.
both will work very effectivly if done together. and you will have clearer ,deeper, louder bass for blocks.. trust me as i did the same
"i was gonna fix my car but then i got @&#$"
1995 bonneville se 114,000 miles and crashed the f up due to an idiot driver with state farm..then repaired 100% by yours truely..1988 bonneville sse 74,000 miles. my best car yet. never let me down.. (edit: o.k just once thus far on 1-14-08 )