Philippine oil refiners said yesterday they were ready to comply with the government's plan to speed up the phaseout of leaded gasoline in heavily-polluted Manila by January. But industry executives said the country's refiners would have to invest billions of pesos to be able to meet higher petroleum product standards by 2003 and 2004. Joey Campos, manager for strategic planning of Petron Corp , said the firm needed to invest about 4.5 billion pesos to meet cleaner petroleum standards by 2004.