I think your best bet would be to replace with a stock one in good nick. I just sold mine for $320 with lines and it was in good condition so there easy to find for a good price.
If you replaced with a high flow and tuned with the safc and the current mods you probably wouldnt have alot over the stock maybe 20rwkw extra. Is that worth $2300 + install.
Just getting a highflow without other supporting mods is like doing less then half the job. You really need larger injectors,boost controller, z32 afm and a complete replacement ecu ontop of what you have already.
Is that $380 for a stock turbo or high flow, cause thats way to cheap for a high flow?
You probably wouldnt get any more power with a stock turbo replacement and tune on the safc but the response and delivery would be so much better.