I've installed k&n filters on all the vehicles I've owned. The HP gain is not something you can notice, but I purchased the k&n filter mainly for basic maintenance and upkeep. One and done. :cheers:
I found the same as [MENTION=50507]CookieRoe[/MENTION], sounds louder, didn't really notice anything other than that. Cleaning it and re-oiling it did become bother some, ran into a few times where something came up and needed to run out but filter was still drying, eventually I bought another one to have one ready. After awhile I gave up and went to off the shelf. Just my 2 cents, if you like it then go for it.
My K&N has over 100k miles on it. Looks a bit worn, but it still gets the job done.
I used to keep a stock filter laying around, then it got thrown away at some point but wasn't a big deal because I always had the motorcycle. Now I just drive the Tacoma if I need to go somewhere.
Anyone destroying a MAF is over oiling and it really doesn't happen as often as everyone thinks it does. I also had a K&N in my bike, and the one in the 4runner is the one that I've had in my 4.0 Tacoma since it had 100 miles on it (100k now) I just swapped it out since I don't drive the Tacoma as much. No problems on the Tacoma MAF.
Over, Under, or Properly oiling it still results in MAF becoming dirty/failing. Doing used vehicle inspections for the dealer, more than 3/4 of the vehicles that had issues that were traced back to the MAF also had K&N filters in varying degrees of "oiling."
They have very poor filtration capability, which they offset with an oil film; which both works and doesn't work when it gets sucked into the intake and coats in inside of the intake with tacky oil. I'd rather use a dry filter if you're going to go the route of less filtration for more "power." It's just not worth it to me to run an oiled filter in a MAF vehicle for all the problems I have seen them cause in the long run, if it's a MAP vehicle; it doesn't matter I suppose (I mean the intake is still getting coated, but whatever...)