ECU Upgrade Twin Turbo On the turbo model, an ECU upgrade is the single most dramatic jump in power you can make without going to larger turbos (which also requires an ECU upgrade). By changing the air/fuel mapping, removing the top speed limiter, increasing the rev limit, allowing increased boost and modifying other parameters, 60 horsepower is added. Reliability is not compromised under normal aggressive driving. Add exhaust and Hi-Flow Intake System (to make the Stage 3 kit) and get a reliable 403 horsepower! 90-95 300ZX Twin-Turbo. A core charge fee of $500 applies.This fee appears as a handling charge on checkout and is refunded to you when we recieve your old ECU unit.