I had Vti Oriel Prosmetic 2002, Lovato kit with 60kg cylinder. My car pickup was fine and in the city I used to get 80-100kms. And on the motorway I got around 185kms many times and this is with AC on the speed of 100-120km/h.
I believe CNG kit matters but the kit proper adjustment is very important. Lovato kit in my experience is better in regards of car pickup and consumption.
But the most important is the adjustments of gas, etc. Because on the same car, when I installed the same kit, I used to get aroudn 50-70km and on highways 90kms :-). I got it tuned up by another CNG expert and yahoo it worked really well for me for more than a year. Yeah but then I had to compromise with the power/pickup of the car.
I had to choose, if I want my car to run almost the same as its on Petrol and do around 70km per cylinder average or 100+ but with low performance. Oh and by the way, 165km/h tak to I remember I drove it.