A 1994+ MR2T is 240bhp standard. Add a boost controller and intake and you have 280-300bhp for around £500. Add a new clutch, injectors, raise the fuel pressure add water injection and you will get 350bhp+
Speak to Fensport about an engine transplant. They do it to Corollas etc. They have a 3S-GTE in a corolla with 420bhp! They also import low mileage engines.