Say for example I am racing on a private stretch of road.. I pull over.. leave the car on, pour some water over the intercooler and have a run again.. would this do any good?

 

Like the Drag strip?

Not-so-red-and-white-cooper (Rick) Made an $8 water spray system for the intercooler with parts from home depot, that apparently did a great job at lowering temps between runs at the strip. (If you search you should be able to find a thread with some more details on how he made it and the results he experienced)

It's also the basis of many of the water spray systems for intercoolers available commercially.

But if you're talking about going to HPDEs then by the time you hit your flying lap the majority of the heatsoak should have vented and your engine will be at normal operating temp.

 

I dumped water on it at an autocross test & tune once. I don't think it made any difference, and then I was thirsty the rest of the day.