In all honesty a bigger core!

That things looks small!
Make sure the pipe work is 2.5"
3" downpipe
Turbo intake pipe
Clutch
Check all pipes for leaks and replace with silicone if necessary
Check for any fault codes and fix any
Port the exhaust manifold
Maybe a couple of other things i can't think of
And get a custom map from r-tech don't get a generic revo crap
