Yeah that has been a bit of a negative for Garrett based turbochargers for a while, however Garrett do proper T4 twin scroll exhaust housings for GT35 wheels now - so it should be quite doable :) A friend of mine has an HTA3586 with the ATP T4 housing in his new GTR and that is going to be a bit of a monster, too. Should be hitting the rollers soon with a new upgraded fuel system and E85 - I expect it will be fairly silly! Should be able to report results soon.
The same engine/turbo setup was previously in an R32 GTSt and not E85 but met a sticky end: