True CHAT or TACT, neither states pressure (unless you consider pressure to be agitation). Maybe the high pressure is the best form of agitation in this case, it's what seems to be most highly suggested. Just spend longer on the dwell time with either 360i or crb to add time, and use more chemical. Does there come a point you can add too much time or chemical on a tile floor?Well... No. Any successful cleaning process is going to be 95% chemistry. HWE for grout would be what most would suggest.