I will soon be looking for a second hand chipped ecu for my escort, I have seen a few on ebay fetching between £50 and £100, so this seems a lot cheaper than having done at well lane for example, but what is the difference between the different ecu codes, hearts&diamonds or red blue black or whatever? do I have to buy as certain one for my car or will they all be ok so long as its off a s2? Also what is the maximum boost recommended on a fairly standard engine, i.e no uprated internal parts?