Don't do it!!! K&N filters do nothing but allow more silicon /dust / sand into the engine, they turn the engine oil darker sooner and wear out the engine components quicker. I have been an idiot all these years and have fallen to marketing hype. Bravo K&N. I removed all K&N filters from all vehicles last year. Not only has is my oil lasting longer before turning darker, but Blackstone Labs Oil analysis on the Q50 and my GT-R have revealed that the silicon has gone down considerable.
Read this:
https://www.bobistheoilguy.com/airfilter/airtest1.htm
and this:
http://www.nicoclub.com/archives/kn-vs-oem-filter.html
and feel free to draw your own conclusions. As for me engine life is more important than 2-3 more HP at the top of the curve near red line, which is impractical.
Don't waste your time and money, simply buy paper filters the Q50 HEV or non-turbo engine gets no benefit from these these terrible things.
I have been using K&N Air Filters for the last 10 years in all of our cars. In most cases such as the G35 Coupe, EX35, and GT-R, I have found that using the drop-in air filter (like this) is much better than any after-market intake piping + conical air filter combination (like this).
I have tired, compared and contrasted the "intake piping+filter" on the G35 Coupe, Pathfinder, Altima, and GT-R over very long period of time to give them a fair shake, but in most cases, and in all cases of Infiniti cars, the net effect of using an aftermarket air intake + filter has been:
- Engine sound and exhaust sound gets louder increasing the perception of more HP. The reason for this is really because all the baffles are lost by swapping out the stock intake.
- Most of them lose the ability to "ram air" into the engine intake manifold, which the Q50 is actually designed to do. This is of course unless the aftermarket pipes and air filter drop past the radiator (often called "long ram air intake") and come just behind the front grill. If not, then HP is lost rather than gained.
- Most of these after-market ones (especially the shiny ones that sit completely in the engine called "short ram air intake") soak up more heat than the stock plastic piping and thus make the air hotter going into the car, which actually reduces HP and mpg.
- If the filters are positioned just behind the grill, then get dirtier quicker defeating the purpose of longer lasting filters, end up getting completely soaked in rain, the car wash and ice/snow. Worst case for me has been a carwash in winter, where a filter was wet and froze in seconds, denying air to the engine.
- Most of them do not have an alternate emergency by-pass opening so that if the above were to happen, they could let out the water before it gets to the engine and also serve as an alternate intake for air.
