Offshoreonly.com - MSD or Crane Box with a 496

The Crane and MSD boxes would be very difficult to make work on a 496. Their is no central ignition module and the ignition triggers are in the ECM. You must understand that the reason the worlds engine builders have gone over to the coil near plug ignitions is to make sure coil recovery time is longer and the energy for each plug pulse is much stronger in Joules than the old single coil distributor type ignitions where the Crane and MSD boxes really were an improvement in spark energy and duration. The multiple sparks in the boxes and spark duration improvements were helpful and worked well in older single coil ignitions. The new coil near plug ignitions like the 496 can be improved slightly in marine applications by eliminating the longer plug wires Mercury and Volvo deliver on their packages. Our new coil re-mount plates relocate the coils under the exhaust manifolds close enough to the spark plugs to allow the GM short spark plug wire sets to be used which will deliver a little more spark energy to the plug. These plates were actually developed by us to allow the use of a clean 496 reworked valve cover with our new polished stainless cover plates, bling development and clutter eliminator motavation. (picture attached on one of our HO600's with the coil remount system)The stock coils on these engines produce a good strong zap to the plug as well as a spark variation based on load and rpms. I know MSD now makes some LS1 style coils that might mount in place of the stock units, but I really doubt they would be off any real horsepower benefit, though they might deliver a hotter spark at idle on motors with bigger cams under load up conditions.
I guess the bottom line here is don't go looking for air cleaners, spark boxes of simple inexpensive magic devices for the 496 or any High Performance marine motor.
Speed costs money, how fast do you want to GO!

Ray @ Raylar