Te 250 race wireing loom

Hi guys, I have a 2008 te 250 with a 310 kit before the 310 kit was put in it had a race loom, now it's back the dealer put the standard loom back on I am wondering why he did this does anyone know why ???
Also on close examination on the standard loom you have the resister plug for when you take off the o2 lamda sensor, on the race loom there is no place for the resister, so is it built into the loom??? And can it break or stop working ????

the harnes removes alot of the extra loops for lights, blinkers etc. rather than having all the dead ends taped up after you remove alot of the extra non essential items