Entry-Level SPL (~145 dB for under $4000)

Subwoofers: 4× 12" competition drivers, $1200
Example: Skar Audio EVL-12 ($300 each)

Amplifier: Single mono amp, 5000W @ 1Ω, $800
Example: Taramps MD 5000.1

Enclosure: Ported, self-built MDF, tuned 50 Hz, $300 materials

Electrical: - 2× AGM batteries ($400) - 250A alternator ($550) - 0 AWG wiring kit ($150) - Distribution block and fuses ($100)

Total: $3,500 + labor

Expected result: 144–148 dB @ 50 Hz

Competitive level: Regional competitions, street class