The key word here is "discernible". He doesn't mean it isn't happening, just that it won't be perceived by most. If the lag is so small that it can't be perceived, then that is great...this is why we are asking the question. And, as he explains, the cooling efficiency is very noticeable so that would outweigh 100 milliseconds of lag (not a real number, just an example) in conditions where the larger IC is needed.
Finally, it still doesn't mean folks shouldn't research and select an IC that best meets their own needs (climate, engine output, usage etc.). We have a quite a few different options, so again, so this angle is always a good one to consider when choosing your IC. Over-sizing for an application can reduce performance.
I found a couple good articles on the topic, just so that you don't think it is just me making up this information
https://www.linkedin.com/pulse/2014...er-sizing-for-turbocharged-engines-foundation
Excerpt: A well rounded design is one that removes heat efficiently, without creating a pressure drop that negates the gains from doing so. The main factors that come into play here are heat transfer area, internal flow area and internal volume. Heat transfer area is the total area of all of the fin packs and plates in the core. Internal flow area is pretty straight forward. This is the total area that charge air can flow, internally, through the core. Lastly, internal volume is simply the flow area multiplied by the channel length.
Larger internal core volumes contribute to turbo lag and a loss in throttle response, as the entire volume must be pressurized before that amount of pressure will exist in the intake manifold.
This one goes into the math of calculating "IC Lag":
https://takemebeyondthehorizon.word...turbocharging-part-7b-intercooler-efficiency/
If you Google a bit, there are many other sources where you can read up on this topic.
