I'm fairly sure Toyota/Lexus ECU's and Fuel pumps are encoded to stop people tampering with them and remapping. Breathing mods, exhaust, manifold etc are your best bet but can be costly for the few bhp gains you may see. I have seen people piggy back ECU's but thast when they have added a turbo on a petrol on a very low boost, but I'm no expert as others said just be careful.