Sir
Do not hook your JBLs @ 1 Ohm or 8 Ohm, they are both extremes.
Hook JBL's in series/parallel, that is, Voice coils wired in series, speakers wired in parallel for a 4 ohm load.
Sound Magus X1502 is a good AMP, and it will definitely make your JBLs in the right power band.
the "Big 3" wires are:
1) Battery negative to chassis
2) Alternator to battery positive
3) Chassis to engine
Sealed Enclosures can take much lower frequencies then ported one.
Try a good quality sealed one with 5/8 MDF and strong bracing, seal all corners air tight with silicone and use screws, make each SUB separate within enclosure.
Fix the Enclosure in your trunk, it should not move with bumps.
you can find an Alternator 80A of 9th Gen Xli from shershah in good condition for around 1,500Rs, consult with a good electrician, if he can fit it in your car.
Also check if your alternator belt is in good condition and both battery terminals are good conductors.
Stinger 10 gauge wiring is enough, if the total length does not exceed 10ft, will cost you around 1K Rs.
Else, use a 8 gauge stinger, which will cost you around 3-3.5K Rs.
Do not crank the Subs too much, JBLs are not reputed for overrating.
Regards