DYNO-PERFORMANCE: We’ve had results from DYNO testing on a stock 440SX Thunder-Jet engine. We tested the stock Hitachi CDI, then tested again using the FIREPLUG CDI. The DYNO measured 2~3 horse-power gain in the mid-range with the FIREPLUG CDI installed on a STOCK engine. The DYNO doesn’t lie. This was obvious with the quicker throttle response, stronger mid-pull, easier starting. This due hotter spark with the FIREPLUG CDI.
DESIGN BACKGROUND: The FIREPLUG CDI is a high-performance replacement ignition unit for your Vintage Yamaha. Other improvements from the original Hitachi CDI is the elimination of the rev-limiter, which the Hitachi CDI utilized to stop over-revving. This was a huge disadvantage for modified engines, as the maximum RPM was limited by the CDI box. The FIREPLUG allows the engine builder to determine the RPM range. The FIREPLUG CDI provides a higher-energy output. This translates to quicker starting, quicker throttle response, stronger pull & cleaner burning combustion.
The FIREPLUG is manufactured using the best available industrial-grade components. The FIREPLUG is not a high-volume / mass-produced imported device. It doesn’t exist until an order is received. Ask anybody currently running our FIREPLUG CDI ignition unit.
This SX/GPX CDI has been on the market since 2001. We have hundreds of this model running out there, continuing to provide excellent performance and reliability!
There is not a better CDI available for spark energy or reliability…period!





