BEST Spark plug - 383

fuel injected I run the iridiums
non injected I usually run the v powers.
with full msd I might be tempted to run the iridiums thought.
Heat range all depends on what you are doing with the engine.
On my 115 outboard I run a 2 range hotter then stock plug because I am starting and stopping it a lot on my newport I am running the recommended heat rang (with a full msd system) for all around driving, the aspen I am 1 heat ranger hotter though. (also full MSD)
The dart is also a stock heat range (orange box)