In our experience with tuning almost every combination of hardware out there, the Do88 intercooler is one of the top performers that we come across.
Of course, some 1 off custom FMIC setups may perform better, but in the realm of stock location intercoolers, Do88 really knocks it out of the park. And as others mentioned, the benefit vs. cost is really well stacked in their favor.
The IE V1 intercooler was great if you ran an upgraded main radiator as it was slightly thinner than their V2 and some other intercoolers on the market, but V2 was definitely a significant improvement in the cooling department. Without back-to-back test data on the same vehicle under similar conditions, it's hard to make an accurate comparison against the Do88.
That said, Do88 is still our preference in the grand scheme of things having seen many different hardware setups.
Please see my reply above.
I see that you have edited your claim.