-open loop mixer LPG kit - basic carb type LPG system. No feedback system to adjust the A/F ratio on the fly. Fuel consumption would be slightly poorer than with gasoline. Some degree of engine power loss especially at the higher RPM. Prices would be around P23K to P25K
-close loop mixer LPG kit - basic carb type LPG system upgraded with a feedback loop via oxygen sensor (or a tap into stock ECU signal). Fuel consumption would be slightly poorer than SGI but better than open-loop mixer kits. Some degree of engine power loss especially at the higher RPM. Price is around P25K for the basic kit (EROOM/DENSO)
-SGI LPG kit - basically a basic EFI system refitted to feed LPG into your engine. This would have a feedback loop either via oxygen sensor or directly tapping into the stock ECU signals to adjust fuel flow. Properly tuned, this kit would give similar fuel mileage figures as with gasoline. Very minimal engine power loss. Price is around P39K (GREENFUEL), P40K (GREENGAS) and upwards.