GUYS, thank you very much for your replies. I do not know, how to turn back the notifications for this thread, I thought, nobody is bothered with my ongoing crap, it turns out quite a lot of you are...
Anyway, I'll attach pictures of my header pipes and the plugs. Plugs, again, look pretty much the same, probably a bit richer, but still nice tan coloured. There is oil on the threads of one of the plugs, but it could have been oil seeping past rings, whilst bike was on the sidestand.
Dave - there is little resitance and slight dragging at the rear wheel, and the bike is easy to push. But as we discussed in an another thread the brakes must be dragging whilst the bike is on the move, as the rear rotor gets hot to the touch even if not used. I have sourced a low mileage rear rotor for a song, so I will replace that and check, if it is not warpage or such, that is making the rotor touching (as the whole brake fluid path - master cylinder, pipes, caliper etc were serviced very thoroughly 4-500 kilometres ago). I did not replace one injector, I have sourced a original K75 one and I will keep it with me just in case the one with the cracked plastic body bites the dust. I did open the fuel return line, when I had this problem with the burning fuses, even though fuel was flowing just fine with the pinched line. I do not know, where to check the ratio, I had a poke around the final drive, but could not see any numbers anywhere. Probably I need to clean parts a bit more thoroughly :) In fifth gear gauges move in unison, however tach needle is sitting higher than the speedo
Martin - TPS clicks, as it should and upon releasing the throttle rpm drops for a fraction of a second nearly to zero before bouncing back, so I guess it tells the computer to shut of the injectors, as it should. Fuel hoses and fuel filter were replaced very recently, back in September - October time, some 1000 kilometres ago. I did not check rail however, I might do that too in the near future.
As far as I am aware, I do not have any vacuum leaks anymore, I used to have massive ones, but I replaced quite a few parts and now RPM stays the same, no matter how much starting fluid or carb cleaner is hosed down on the joints. Exhaust gasket too was replaced recently, just when I serviced my clutch splines and the muffler had to come off anyway. BTW backfire is not the right word, it is more like bubbling, or slight afterburn when throttle is closed and bike is coasting. I am not too keen on buying yet another set of specialised equipment but it would be interesting to see my CO2 levels (alongside some other stuff, fuel pressure, compression, etc, but stuff is veeeery slow to arrive from China).
Gryphon - I've never checked the thermostat, so that is another thing to test. It is very balmy here at the moment, as it is unseasonably warm with 15-20C. I would think, this temperature is just about ideal for our engines. Also whilst I had the Tucano installed, bike gone as warm, as it would in early summer, actually making me remember, how it was burning my legs back in August :)