Intercoolers will achieve a temperature drop, yes...but the temperature that the intercoolers would have achieved would have been lower with a more efficient turbo at that flow rate (and therefore lower inlet temperature for the intercooler). You can't raise the inlet temp on an intercooler 200 degrees and expect the same exit temp as before. A higher temperature difference between the intercooler temp and ambient temp does raise the heat transfer rate, but not enough to achieve that.