The long tuned length runners on the OEM magnum intake are optimized for cruising speed so you might lose a bit of bottom end/low speed efficiency. My memory is hazy but I think they were setup for peak efficency at 1800rpm. I think anything above 3000rpm you will begin to see gains with an aftermarket intake. I know mopar performance made several ECU options of the OBD-1 system in your 1994 but I don't recall if any of them were calibrated for the mopar high rise magnum intake.