The powertec v8 is based upon two hayabusa engines afaik and is around 360bhp in the radical sr8. and yes it is hugely expensive.
There's nothing wrong with forced induction. I'm just much more impressed with high power NA engine then i am with a turbo'd engine. Plus the added weight and bulk of turbo, manifold, intercooler and piping. I'm just not a fan of turbo power for light weight applications such as 7s. and i dont really like power delivery but that's just me.