if i was in your shoes with $1000 to spend to reach 150 HP, i would do a light-duty 5SFTE turbo setup running @ 5psi. I'd be on a budget, meaning i'd probably source the parts for it from junkyards (
www.car-part.com) and individuals on MR2 forums (
www.mr2oc.com). This would include the 3SGTE manifold and turbo. I would get the stock oil pan fitted for the turbo oil return line, and use a 3SGTE MAP sensor, and injectors for fuel, controlled by a cheap SAFC unit which you could get for under $200 for sure... the rest of the money i would spend on a boost gauge and a decent intercooler setup and thats about it.