I can only say I have had no issues with them, they seem pretty resistant to fouling, as I drive like an old grandad sometimes, and they never do anything but behave right.
I had some 071's in there at one time, they did the job ok, but just seems more eager with Ik31, if on coilpack though I can defo recommend a ACCEL coil part number 140018, this is the early type coilpack, about 40% more energy and according to the blurb better spark duration, certainly makes a difference though, as I am looking now for one for my other halfs astra.
tabetha