There are a couple of threads on this issue here: http://www.svtperformance.com/. Apparently, the 99 block is the strongest of the 96 - 99 versions (made in Italy), while the 01 is the weakest - made here. Anyway, according to the threads, as long as you don't get greedy (ha!) and keep the boost and tune within parameters, it may last two years. Without a forged buildup, just playing with fire.