Ok, the topic has been beaten to death, but a lot of the info on the net seemed to have been removed.
Yes, I know the hks gt2530 and the garret gt2860-5 are essentially identical with very little differences. And yes, their performance is also almost the same. However, if given the choice between a set of these two turbos, which one would you take (assuming price and condition of the turbos are the same)? The gt2530 are tried and true, but they're older (technology) turbos. The gt2860-5 are relatively new with (possibly) newer technology, but they aren't a "true" bolt-on as the oil lines need to be modified (no biggy).
I've done quite some reading on the (performance) comparison of the two, but there seems to be conflicting information from different forums. Given the same engine set-up for a mild rb26dett, the gt2860-r will give a slight better response (earlier spool) but the gt2530 will have more to offer higher up? or is it vise-versa? Has anyone experienced both turbos? I know, I know....the difference is probably so little that it really doesn't matter, but just for argument and technical sakes.