Ok. Let me tell you a story. My friend has two kicker 15" L7's and our box is about 6.5-7ft tuned to 42hz(kicker reccomendation higher than average tuning!). When we had a Kenwood KAC-X811d on it they were getting about 1000W MAX, 1%THD@12.0V!!. It sounded decent, porbably louder than almost all peoples pairs of 12's and W7's. Then he decided to sell me the amp (sig) and he got an orion 2500D with 1/0 guage. The car has a stock luxury package chrysler vehiucle probably can withstand 2200w for short bursts. Ok when we swapped the kenwood for the orion, the difference was very very insane. It was by far the loudest vehicle in our town of about 15,000 people. It was pretty crazy and our box was built very very well, double thick face, interior resin. Then we took his back seat off and HOLY ****. Since our box had the port coming in the bottom of the rear seats wtih the subs facing upwards, (ass half backwards crx box basically) there was major cancellation in the back of the car with the subs facing that way. When we took out the seat OMG WE COULD NOT SIT IN THE CAR, WE ONCE COULD NOT EVEN CHANGE THE SONG THAT WAS PLAYING UNLESS WE PLUGGED ONE EAR AND LET THE OTHER ONE GET MURDERED! We had the kenwood metered 5 mins after installing the L7's, 04 model, into the box, still stiff, with 1000watts from the kenwood and 4 guage wire and major insulation and cancellation in the rear we hit 139.0 on the new terb lab. With the orion, 1/0 guage, and removing the insulation from the rear seats, and the 6x9s i would guess that it had better get close to 146.2 on the TL thats only a 7b increase and we spent quite a bit on the upgrades. Hope this helps, if you really have the 1800-3600 watts on tap with a good battery, then go for it and get put them in the 6ft box. You could always sell them for a setup that loves the 6ft gross box! I dont know what i would do lets see what others think. Sorry i know this post is really confusing im ****.