TAIWAN'S benchmark stock index soared to an eight-month high on continued strong bidding by foreign investors amid hopes that foreign interest would drive Taiwanese stocks as high as Hong Kong shares. The weighted price index jumped 178.23 points, 3.75 per cent, to 4,929.81 on volume worth NT$93.87 billion (about HK$27 billion), the heaviest since March, brokers said. ''There's an influence from Hong Kong, and people hope the market here can be like that,'' said Henry Miao, a dealer with Jardine Fleming Taiwan Securities. ''Some people sold at mid-morning to take quick profits, but more people jumped in. The buying craze just cannot stop at this moment,'' said Albert Lin of Golden Securities. Taiwan's index has now soared 30.9 per cent from a recent low of 3,765 in mid-September. Traders said a 25 per cent increase in foreign money in the market - to roughly US$2 billion from $1.5 billion in mid-September - was behind the rise. Meanwhile, Taiwan's Investment Commission yesterday announced that foreign investment by Taiwanese had jumped 80 per cent in the first 11 months of 1993 compared with the same period last year, but investment from abroad declined six per cent. Taiwan approved 298 investment projects by local firms worth $1.53 billion, with the United States and Vietnam being the most popular investment areas. The figure does not include Taiwan's investment in China. The island has become the mainland's second largest investor after Hong Kong, with projects worth an estimated $10 billion by about 10,000 local enterprises. Approved foreign investment in Taiwan in the 11 months dropped to $1.11 billion against $1.18 billion in the previous corresponding period. The banking and insurance sector was the most favoured area for Taiwan manufacturers, followed by chemicals, the commission said. Japan remained Taiwan's biggest foreign investor in the period, with 75 projects worth $250 million, down 37 per cent in value from the same period last year.