Actually have two China sets, metric and standard, purchased from the cheap tool store, with a little lube have never broke them. I am not machining though, just polishing up damaged threads and such. I have made a few grade 5 and 8 bolts longer without a problem.
1996 ZJ - That 2nd Oxygen sensor, yeah some serious butt connectors and heat shrink there, how is that for off road modification! - Still stock.