Sirs
@scorpion80
Thanks for the positive comments.
@murtnabila
Sir, unfortunately JL Audio and BA are only personal imports, not readily available, and we can not afford them in this part of the world, because we do not have $$$.
@JOJ
Sir, below mentioned speakers are all much better in frequency response and overall sound quality then Kenwood 718, but are less is bass output, due to their shape and weight, you should not concern the bass output, and only care for the overall sound quality, since you are having a dedicated SUB for Bass.
The 6.5" budget Components have the better sound quality even compare to the high end 6 x 9" multielement like polkaudio db691 or Alpine Type R, since they have a dedicated tweeter and crossover network for routing high and low frequency to the smaller and bigger driver, where they suits best.
6.5" Components
Sony GTX 1620 round Components
Alpine SPS 600C
6 x 9" Speakers
JBL GT5 963
Alpine Type S SPS 69C2
All other speakers, that I have recommended in earlier post are much better in both sound and power output hands down.
JBL P963 are really hard to find, I would recommend Polk DB 691 or Alpine Type R.
First you have to change your HU/Cd player to a decent one, since it is the brain of your sound stage.
I would recommend a used Pioneer 4050UB for 6K Rs or the Alpine CDE 9873 with orange buttons that comes in the 10th gen Corolla or 5th Gen City for 4K Rs.
Secondly you have to upgrade the AMP, a 4 channel one.
JVC KS AX4504
http://mobile.jvc.com/product.jsp?modelId=MODL027904&pathId=64&page=3
Kenwood 8401
Kenwood - KAC-8401
Sony ZR604
http://www.sony-mea.com/product/xm-zr604
They will all cost 8K rs or less.
For SUB, I would recommend
Either you can go for the Kenwood 4K Rs
Kenwood - KFC-XW1024D
Alpine for 6.5K Rs
Alpine Electronics of Asia Pacific Co., Ltd.
or
JBL for 5K Rs
http://www.jbl.com/EN-GB/Products/Pages/ProductDetails.aspx?PID=GTO1202D&accT=1&tsT=0&ovT=1
Whichever is available, and genuine, they are all premium drivers and have much better overall response then Pioneer 3xx Series.
Any AMP can power those SUB, the main thing is if you are not satisfied with 600W, then you have to upgrade the AMP to 1,300W, but you should listen first.
For a 4 Channel AMP:
the 2 channels can power 2 speakers, either the front 2 round 6.5" Components like Sony GTX 1620S, if you install them or the rear 6 x 9" like Alpine Type R.
The remaining 2 channels can be either bridged for the SUB or connected independently to the Dual voice coils of SUB.
Also get a nice 10AWG wiring of scorpion, and a nice sealed enclosure sized accordingly to the SUB you choose.
Regards