The XE with 2E Engine is insane in Performance while it Rocks on Economy on CNG (not Petrol). For better Performance use better CNG Fitting and Settings from some Expert. Usually to improve the pick on CNG Kits need to be tunned.
I think with 2E 120 kph is good speed, and its pathetic on Uphill with CNG.
Use good quality Spark Plugs, especially check the Air INtake COnditions and adequate Flow available, Tune your Engine for CNG.