Looking to upgrade the turbo on my setup down the road, and I was looking at the GT28RS. I've heard it was a direct drop in using the greddy manifold so I wont have to redo my downpipe (again). Anyone know which model would specifically work?

Probably looking at the GT2871R

 

it will fit as far as being adaptable to the manifold, but im guessing its not going to mate with your DP perfectly

 

no