Originally Posted by gonzoY5
So since we're doing the question game, couldn't running a colder plug in this case work instead of adding a shim? Maybe some of the engine gurus can answer.
Having done my research I have gathered the following:
Adding NItro = Advance Timing
Adding Shim = Retard Timing
Colder Plug = Retard Timing
Since you're adding nitro the timing is advanced. You want to add the shim to bring back the timing. But wouldn't the colder plug do the same? Adding a shim, will reduce compression which should reduce power. Why would we want to do that?
Just random thoughts and questions that run through my mind, thought maybe I should throw them out there and see what others think. So rant away

Very good question!
Higher compression with cooler plug V.S. lower compression with hotter plug
Under well tuning both of them may work fine. Actuality it have different power band. Higher compression has better acceleration and lower compression has better top end.