Philips offers several + bulbs, ranging from +30 to +60 to +100. Two questions: 1) is there a life span difference between them? and 2) do any or all of them actually produce the advertised degree of increase in lumen output from stock bulbs? Also, assuming there are extra lumens in these bulbs, would you see a difference on the road? All responses will be much appreciated. Have tried to research this and have seen many conflicting reviews on Amazon and other sites. Am assuming Philips is better than Sylvania Silver Star but am willing to be corrected by real world experience. Thanks again in advance for the input.