Difficult to say without pictures, or detail of where it is fouling.
Assuming you are fitting the kit correctly according to the instructions, then it could be excessive play in your side stand, or side stand bracket bent, or side stand bent, or modified side stand, or.................
Ive just fitted the 40mm lower kit to my R1100GS and thought it was going to interfere but its been fine. just have to be careful when putting the side stand down that you down clip the gear leaver as it makes all ya mates laugh.