Why the Top Palace so expensive? Worth it?

If I want to install the omni speaker to my Head Unit(no amp, 4x stock woofer), what's the best way(practical way) to install omni beyond speaker?
1) tapping the rear speaker wiring in series?
2) disconnect the rear speaker for omni beyond to get full rear power?
3) Adding the low/high pass filter?

This post has been edited by jasonws: Oct 4 2019, 06:15 PM