if u dun mind used unit, u can consider the following with a bit of top-up from ur budget:
1. Polkaudio MMC650 6.5" comps + passive
Price: RM350.00
used unit in mint cond, local set.
2. Aulux 4ch amp AXS-854
Price: RM380.00
this amp is NOT bad sounding!
if its new it should cost more than RM1.8K for both items
total: RM730.00 only
http://www.polkaudio.com/caraudio/products/recent/mmc650/not the actual unit. i can mms to u if you're interested
definitely have a lot of improvement over SQ as compared to stock
since its a 4ch amp, u can have future option to add the following:
1. sub
DLS Reference Series MW10D 10" with DLS Grill
* comes with ported enclosure built by autogadget
Price: RM400.00 used unit
or
2. rear-field speakers

prices above are excellent for newcomer or people who have budget in mind who wanns good quality stuff..