A sometimes over looked turbo is the IHI vf turbos off scooby's, these have roller bearings and are almost as good as the GT28 turbos. IHI's go for £300ish on ebay. Torque or high revs kill rods. 300hp and 280 torques is safe.
Maybe make your own manifold, 20v turbo manifold flange kit VW 1.8 Turbo manifold flange KIT GT28 GT2871R S3 Cupra | eBay
Maybe make your own manifold, 20v turbo manifold flange kit VW 1.8 Turbo manifold flange KIT GT28 GT2871R S3 Cupra | eBay