Oversized every time.
Think of it like blowing/sucking through a straw...... The skinny one is the equivalent of sucking on a really long thin straw... Lots of effort needed to shift a small amount of air....... With a larger diameter straw you shift a lot more air with a lot less effort...... The less effort wasted here the better, especially on a small framed turbo that runs at 100% of its capability once tuned.
I'd also recommend getting your money back for the Superchips sh*te and getting a proper tune done, whether it be generic from the likes of Revo, APR etc. or a live map from the likes of R-Tech etc.
Any of them will be a LOT better than the Superchips/Bluefin sh*te