GT2871 (86 hotside) will get 400 and more. We have done many with 400+bhp. When you go to that level on an
Ibiza, its the other components that start failing. The gearbox isnt up to it and you will need cryo treated gears as a minimum, the driveshafts are on their limit too.
Minimum is rods, but I would advise pistons too. I have heard of standard pistons go to 650bhp in the US, but I wouldnt go that far on them.
See my build thread in the link below for what ive done to get over 400bhp.
Alex