[kpeztruck]

I used the MSD Atomic EFI on a '56 Belair. This was an all number matching car, so the customer did not want any new holes or large modifications. I used it returnless and set everything up. Still using the factory distributor with an electronic conversion that had been previously installed. It developed a terrible bog at part throttle, and would stall at the most inopportune times. The A/F ratio would show 18-24:1 when in condition. After talking with techline(and there is one guy that is sharp on these things), setting everything up as he desired, he decided that my kit did not come with an addendum to install a fuel pressure isolator from a Honda that would prevent surges in fuel pressure. he said that the ECM was making decisions on a measured fuel pressure, then by the time the action was carried out, the fuel pressure dropped and it did not get enough fuel. Installed the isolator as instructed and now the car runs great. Customer is real pleased with performance and fuel mileage. The tech guy did say that it will auto tune, but if the info/manual calibration adjustments start off incorrect, it will tune itself into a corner as mine did. Overall, I'd do another one for a driver hot rod.