My 496 was dynod with MSD and MP. MSD made 3 more hp over the MP. I'm using MSD pro billet; with this unit there is no box to clutter up your eng compartment. What was most interesting was the MSD unit was much more stabe throughout the test. In other words the output was more consistant. This was evident on the dyno. I don't know if you will see it on the street. I beleive the MSD to be more reliable than the MP. FYI the MP distrubuter was a new unit; pulled it out of the box and installed in the engine. The curve on the MP unit was way wrong; full in was not until 3600 RPM. I understand dist need to be dialed in but for a "performance distributer" this one was pretty far off.