Anyone that has experience with GT series turbos though will tell you that they will burn some oil, that's just the nature of the GT turbos.

 

GT turbos shouldn't really "burn" oil. They do use very little oil though, so depending on how much oil pressure the turbo sees it could have issues with smoking.

Most of the ball bearing carts you see from Garrett have a built-in restrictor which in my experience has worked perfectly for most applications on GT catrdiges. Some of the ball bearing Garrett T-series cartridges (BB 50-trim, 60-trim, T67, etc) require an additional restrictor or they may smoke though.