Yep, I made 400 (+? it is an auto after all) on the Blitz return flow. Which, from the outside looks exactly like the cooling pro one.
But as mentioned, it could be very different internally. Or, perhaps there's a correlation between people who choose cheap intercoolers and other setup issues or corners cut elsewhere. nfi.
Also yes, while I used E85 in my setup with the Blitz, it made well, well, well over 300+ on 98. Enough that the intercooler didn't even think to become a restriction at all. I never pushed the boost or timing on the 98 tune, it was there just to drive around on when E85 wasn't available.
Point being though, "you can't make more than 250 on a return flow intercooler" is false.