Ball, like all RB singles.
There is no such thing off the shelf. All Garrett, BW, etc turbos are intended to be MASSIVE upgrades on the shitty 1950s technology that defines the stock Hitachi turbo.
No turbo that you will find on eBay from the usual scumbags is worth the $400 they want for them.
If you want a good "slight upgrade" replacement, then Hypergear's lowest end highflows are the closest sort of thing you can buy. Oh, and there is no problem buying from HG all the way from the US. You do realise that the world is round, right? And it is therefore possible for planes to fly all the way around? It's amazing what they can do with cardboard boxes these days.