heavier cng cylinder will recuire spacers,which will stifen you car rear suspension... so those who will be sittin on back seats will curse you guess you wana switch to bigger cylinder due to cng load sheddin thingy?? if so,i guess stick with 50 and if you run out of cng in load sheddin days, give your car some petrol to run on...petrol was what these cars were meant to run on...keeps engine healthy!