I've been searching on the internet for hours and I haven't found any concrete information. I own a 2006 Civic as well as a ITR. According to my research, I should be using 51356 for the Civic vs for the ITR 51334. The difference between the 2 filters is the size, where the ITR is apparently slightly bigger. If I go to the dealership, it seems they use 1 filter that fits all Honda/Acuras for my ITR, and this filter is equivalent to the 51356 according to my research. My question is.. do you guys think it is alright to use the 51356 instead of the 51334 according to the application guide?