Is this what I've heard about? Supposedly adds 100 HP to the 496....
http://store6.yimg.com/I/azspeed_1786_2082775
Arizona Speed & Marine has developed a revolutionary fuel injection manifold for the GM 8.1 liter engine. The intake manifold has o-ring seals inserted in a groove on the side plenums. This ensures a seal between the upper and lower castings. Intake runners are shaped to provide the cylinders with a straight column of air to pack the cylinders. The injectors are pointed at the intake valves keeping the fuel in suspension, and mixed with the incoming air. AS&M is also fabricating 85mm throttle valves to provide adequate airflow for the new engine packages. The 85mm throttle valves are cable actuated, and have stainless steel hardware to prevent corrosion. The intake manifold and throttle valve can be irridite coated as an option. Irridite is a very good base to paint your favorite colors on and also offers corrosion protection. Overall height of the intake manifold measures 22-1/2" from the center of the crankshaft to the highest point, it's only 1" taller than the OEM manifold. The complete conversion package contains the following items:
- Manifold Base
- Manifold Plenum
- Custom Fuel Rail
- Billet 85mm Throttle Valve
- MEFI 4 ECU
- MEFI 4 Harness
- Calibration of the ECU
- Adjustable Fuel Pressure Regulator
- -6 Fuel Pressure Regulator Fitting
- Throttle Position Sensor for 85mm Throttle Valve
- Idle Air Control Motor for 85mm Throttle Valve
496 Man Pk $4,581.25