* Weak yen drives exporter shares higher * Abe may use strong market performance as ammunition to stick to initial tax hike plan - traders By Ayai Tomisawa TOKYO, Oct 31 (Reuters) - Japanese stocks rocketed more than 5 percent to levels before the global financial crisis on Friday, after the Bank of Japan stunned markets by easing policy further in a move prompted by slow inflation after an April tax hike dented economic growth. The central bank decided to increase the pace at which it expands base money to about 80 trillion yen per year, up from a previous target of 60-70 trillion yen. The BOJ also decided to increase its purchases of government debt by about 30 trillion yen and extend the average duration of JGB holdings to around 10 years, and decided to triple its purchases of exchange-traded funds and Japan real estate investment trusts. The Nikkei benchmark rose 5.1 percent to 16,455.84 in mid-afternoon trade, the highest level since November 2007. "Most people thought that easing would start in January, and only a handful people thought that they would do some easing in October," said a senior trader at a foreign brokerage. "It's definitely a surprise." The Japanese economy has been plagued by weak consumption after the government raised the consumption tax in April, prompting government ministers to call on Prime Minister Shinzo Abe to delay a planned second consumption tax increase next year. But the senior trader said that Abe may use the strong stock market performance as ammunition to stick to the initial plan. The dollar soared to a near seven-year high above 110.67 yen , lifting exporters. Toyota Motor Corp jumped 3.7 percent, Honda Motor Co and Tokyo Electron Ltd soared 3.8 percent. The broader Topix gained 3.7 percent to 1,326.17, while the JPX-Nikkei Index 400 surged 3.9 percent to 12,099.14.