the GT2876 really is pig.
if you want 250rwkw then the GCG Hi-Flow, GT3071 (with a 0.82 garrett housing), or HKS GT-RS put you right into the zone as they are all around the 420-450hp compressor mark.
The GCG unit is the easiest option as it bolts directly back onto the stock gear, the HKS GT-RS comes in kit form and bolts back into the stock location.
Any other option will require a new dump, lines and probably intake mods.
Once you have decent engine management PowerFC, ViPEC or other you will be able to spool any of these turbos with no issue.
If you are happy with a bush bearing then Hypergear is making some cheap bolt ons too.