So you're using information from a friend of a friend? You don't have a 1G with a single turbo setup? I drive mine daily with a single turbo, the only way I would make 250hp is if I cut my boost in half.
All the big companies such as HKS and GReddy in Japan make just as many parts for the 1G as the 1JZ. There were probably 20 different turbo kits produced, three full supercharger kits I've seen first hand, internals, two stroker kits, cams, cam gears, TRD OSGiken and ORC clutches, electronics, you name it and I can get it. If all anyone wants to do is push the 7M or 1JZ that's their prerogative, but new people search these forums everyday and I'm tired of people spreading rumors and perpetuating the stereotype.
If anyone has to ask why swap to a 1G without expecting a serious answer then you wouldn't understand.