^add some port work and port match the intake manifold to the head to that list. The main thing that holds back the 2.6 is gas flow (other than the asthmatic Mikuni carb...) Duration in the cam is the key to improving performance (a number of online forums advise that a high lift cam in one of these engines will actually kill performance) If your engine is using a jet valve head, either use a delete kit or get an all mechanical non jet valve head. Delete the EGR system off the engine as this just kills performance all round and normally is coked up anyway and not working 100% (seal the EGR port in the head and then you can remove the EGR valve with a block off plate). Eliminate the clutch fan from the water pump pulley and install an electric thermo fan. It removes a load from the crank, improving throttle response and works when the engine needs it most (+ frees up engine bay room, prolongs the life of the water pump bearings, potentially improve MPG - too many bonuses not to do this anyway).