I have a 4-channel Eclipse amp for my speakers and a Alpine Mono for my subs. The 4-channel is fine under the back seat since it doesn't work too hard, but when I had the Alpine MRP-M1000 amp under it, it would overheat after a hour or so. Like others said, make sure you have a gap between the top of the amp and bottom of of the seat. The Alpine amp was taller than the 4 channel, so it was touching the bottom of the seat the whole time which wasn't good. I also had a 5-channel Planet Audio amp under my back seats before and it would overheat after 30 min. I'm in Houston.
'98 Jeep Wrangler 2.5L | 4" Pro Comp Lift | 33x12.5x15 Dunlop Mud Rovers | Two 10" Polk Audio Subwoofers | 2 Amps (800w Eclipse and Alpine MRP-1000 Mono) | Kenwood Head Unit | Ham Radio w/ Comet SBB-7 Antenna (Call Sign: KK4BUE) |CB Radio | Hella Vision Plus Conversion with 50w 6k HID bulbs | Lotta Lights |