You can do the test by modifying the voltage to the pump, to speed it up or slow it down. Don’t need a new pump to increase/decrease flow for the test.
Historically, this answer has evaded the masses because of the variables at play. Some people want consistently cool temps, for a long period of time. Some people want low temps for a few seconds at a time. Having a cold source (your reservoir) quickly rushing over the intercooler will cool the intercooler quickly, but the “loop” will come up to temp quickly as well. So at the end of the trip it’ll all be hot. A slower loop will not reduce the temp as quickly but will reduce the temp over time until the loop has equalized. And ice box with high flow is good for racing, and the flow doesn’t need time in the cooler, the colder the water introduced to the radiator the more heat it can remove.
But I’m not a biologist, so your results may vary.