i ran 2 dual 4 ohm coil solo xs on each horse (wired at 2 ohms----full power) and i ran it daily......now when i was cruisin and at just about full volume for almost an hour i did smoke 2. they got extremely hot. i did however have 1 warhorse on 4 d2 (2 ohm full power) for a little over a year and then threw in another warhorse (1 warhorse per pair---1 ohm load on each-----half power 5k each amp---basically like running single amp) my voltage stayed up a little better and my score went up .6db. this was all in a wall that was a daily car. with the 2 amps in i ran that for about 9 months. the cones are still good! they are black and always stunk but hey its kicker. i ripped my wall out and shortly after that the d4 cones i waited over a year on came in, thats when i threw my boxes from my wall into my blazer with both amps at full tilt on the 12s. with the 2 amps on the d2 coils (half power) in my wall best i did was 158.9 peak and 157.1 30 sec average. in my blazer with the boxes from my wall and both amps full tilt my highest score was a 158.3 outlaw. and 156.2 30 sec average. the extra power helped alot! i did have a kicker designed wall in my car for the solo xs as i used to run 1 2500 to each x 12 at 1 ohm to each amp. my highest score was 154.6 when i went to the 1 warhorse my score went to a 154.9 and i was not pleased. i built my own enclosures and the subs performed better then ever and actually sounded good and i went to a 158.3. dont use kicker specs for boxes or else they will not handle it! i had aprrox 1.9 cubes each sub (3.8 internal per box) with i think 4" wide and 12" tall port for 2 subs. i still have the boxes....they are 1" mdf dual face internal braced tuned to 47hz and peaked at 55 in my car. these were designed to get max score without sacrificing too much on the music side but i wanted #s as well. it sounded great! im doing a wall for a guy with 4 18 solo x and 4 warhorses. kicker says 40 cubes internal and 1200 sq in port. i will not have 1200 sq port as thats insane and also i will have about 10.5-11 cubes internal for these. in the 10 cubes the subs wont handle 10 k burps, but a friend ran a solo 18 in a box that was 21" by 21" and 12" seep (sub barely fit) with a 8" areo port coming out the side. he ran 9,000 watts and had over 70 burps and over 30 30 sec ave runs before his cone went. just saying kicker specs=FAIL!!!!!!!!!!!!!!!!!!!!