One of my neighrbours did modding for the 20VT. I think his hit over 500 BHP but he had to rebuild parts of the engine and manufacture some parts for it to let it consistently run at that. In some cases I think he just strips the car and rebuilds everything onto the chassais *shrugs* Mind you.. that was his job.
Little bit of an update - finally have enough money to be able to get the ECU Hurraaah!! £1600 quid of red shiny goodness!!