My new install.

IMO, where ever you put your amps has its positives and negatives. Under the seat they can also run hot, they tend to get kicked by passengers and also, can get alot of dirt inside them thru any vents they have from people's shoes, or dust from the carpet.

In the boot, you eliminate the dirt factor (if you keep your car as clean as I do) the only issue you have is over heating. My old amp (kicker 600.4 - which im selling, if anyone is interested) has internal fan's to keep it cool. But what I will do b4 summer, is install some 12v fans behind the install to cool the amp's. Had it in my Mazda years ago, and it worked a treat, after the amps kept getting hot and cutting out.

PS: Excuse the polar spec camera phone pic... Will post better pics up over the weekend if anyone wants to see them.