So you reckon BNR Stage 2 & 3 would require forged internals? Wouldn't that require the heads to be machined? That itself is a massive job. If you're committed to machine the heads, why not go with a full rebuilt & have a bigger turbo? Supporting mods such as the exhaust manifold will be a bitch to fabricate on the MPS. Doubt that the exhaust manifold from ATP Turbo will bolt on without any issues.
I do understand that the cost for a turbo upgrade with its supporting mods will cost a lot. The last time I calculated it was close to $12K without new ECU!
It's a lot of money to spend on increasing the boost! MPS is such a expensive car to mod!!!