Found this on Ebay - Have seen this before with Mazdas and other vehicles.
Increases the ignition voltage from 12Volts to 16Volts!!!!! $120 SHIPPED
eBay Motors: IGNITION POWER BOOSTER SYSTEM FOR S2000 350Z Si Z3 tC (item 300149374193 end time Sep-12-07 19:50:34 PDT)
IGNITION POWER BOOSTER SYSTEM
This ignition power booster system will directly increases input voltage from 12 Volt to 16 Volt. It is able to automatically reverts to original circuitry when VSD is down. This unit would be boosts horsepower by 8%~12% and yet 12%~19% fuel economy. Increases ignition voltage and reduces exhaust for more power engine output.
KEY FEATURE:
Increase 12%~19% fuel economy.
Increase ignition voltage.
Increase 10~15 horsepower.
reduce exhaust for more powerful engine output.
PACKAGE INCLUDES:
1 set of ignition power booster.
Installation instruction included.
All wiring and harness included.