Sir
Since an amplifier produces more wattage at a lower impedance, 2 OHM stable AMP will give you more power at 2 OHMS (low resistance) compare to 4 OHM (high resistance to current).
2 OHMS draw more power & heats up more quickly, you can blew up your head unit if you use 2ohm configuration SUB & speakers without AMP, directly hooked up to CD player, since head units are 4 Ohm and not 2 Ohm stable.
How you can figure your SUB.
Parallel: A dual 4-ohm voice coil sub woofer with its coils wired in parallel presents a 2-ohm load to your amplifier.
Series: Series wiring lets you configure multiple woofers to one amplifier at an acceptable impedance. Wire both coils in series for an 8-ohm impedance, and then wire two 8-ohm subs together in parallel for 4-ohm total impedance (perfect for most 2-channel amps bridged to mono operation).
Another example: if you have a high-powered 2-channel amplifier, wire four 8-ohm subs per channel (each channel sees a 2-ohm load).
Your Pioneer SPL SUB
TS-W3001D4 Pioneer - Speakers & Subs - Car Entertainment
is rated at 1,000w Nominal power (or Rated RMS), and 3,000w Maximum power.
Since RMS is more reliable standard to compare products instead of maximum power, we are using it as a reference.
Kenwood
Kenwood - KAC-9104D
500 watts RMS x 1 at 4 ohms (900 watts x 1 at 2 ohms), gives you that much power, its a class D mono AMP (means its the most efficient design specially made for powering high performance SUB). Kenwood is even 1 ohm stable (less resistance).
Kenwood is expensive, Sony is a 2 Channel high power Class AB AMP.
XM-GTR2022 (XMGTR2022) : Car audio : Sony
It can give you 500W @ 4 Ohm and around 750w @ 2 Ohm, but it will save you 6,000Rs.
Regards