First of all. Unfourtunately I don't read German so I have no idea what the product sheets you sent me are saying. But here is an overview of what you need to do.
First of all. What type of music will you be listening to? Is it Rock? Hip-Hop? Jazz? Classical? etc. The type of music you will be listening to will determine the type of sub. and crossover so the lower parts of the music scale are sent to the sub. Go to the Car Audio shop, tell them these things and then listen to the set up you like best. In the size of Lexus your driving,,2 subs is WAYYYY to Much. 1 sub is more than enough for the cabin space. That is unless you want to listen at ear bleeding levels.
Yes you want a seperate amplifier to drive the sub. Again, this depends on the sound level and output of the sub. Go to the Auto Audio shop for a demo.
Good luck.
When your done please let us know how it turned out
Paul
Thanks Paul...you gave me a good laugh there...
Its not german, its swedish...and its only product names so I think you could do great on it.
Anyway thanks for reply, I have decided to wait until I get the car so I can see where the "flaws" are.