A RADICAL provincial chief has challenged central-level edicts by saying his region should pursue a fast-paced development policy in spite of the overheating national economy. Mr Lei Yu, vice-governor of Guangxi, said the local economy was not overheated and that it must pursue a growth rate above the national average. ''The problem of overheating does not exist in Guangxi,'' Mr Lei said yesterday at a foreign trade promotions function in Hongkong. ''In the Eighth Five-Year Plan period [1991-95], our economy will grow at annual average of 11 per cent and I am confident that our 1993 growth rate will be above that.'' In defending his province's fast-track development, Mr Lei, nicknamed a ''cowboy capitalist'', said Guangxi had the ''rock-solid'' support of economic czar Vice-Premier Mr Zhu Rongji. During a recent visit Mr Zhu urged Guangxi to speed up its economic construction, according to Mr Lei. As a result, Mr Lei said Guangxi was prepared to go full-steam ahead to rejuvenate its economy by committing billions yuan of capital into its infrastructure, including the construction of five new airports, 14 highways, five power plants and five major ports. Mr Lei stressed that the infrastructure upgrade was of paramount importance as the central government was committed to turning the province into China's passage to the Southeast Asian market. And the vice-governor even quoted Mr Zhu as saying that the central government should offer more support to Guangxi so that it would be able to realise the target. At present, Guangxi received an annual subsidy of 670 million yuan (HK$897.13 million) from Beijing. Mr Lei yesterday also openly praised Mr Zhu for his ''vigour and resolve'' saying soon after Mr Zhu's visit, Beijing had responded and approved the resolutions of several railways and air transport problems confronting the province. While Mr Lei blamed Guangxi's past sluggish economy on a constant state of hostility between China and Vietnam in the past 20 years and a lack of investment on infrastructure, he admitted that the reformist dictum given by patriarch Mr Deng Xiaoping lastyear was the prime driving force. ''We can't isolate Guangxi from what's going on in the rest of the country, it is related to the big climate,'' said Mr Lei in a reference to the ongoing economic flourish along China's coast. But the vice-governor who was transferred to Guangxi last April after serving a four-year term as vice-mayor of Guangzhou however did not take credit for the economic success his province witnessed last year. ''Last year, our GNP jumped 14.5 per cent . . . But that doesn't mean I am responsible for all these. Of course, I have my share of contribution,'' he said.