So I went to put my airbox in today and when I go to put the filter in and it doesn't completely fill the air box like I would think its should.

I'm probably just going to shell out the cash for a k&n stock filter unless there are other good performing air fiters made for the stock air box that fit snugly.

Rotary > Pistons

 

i would try another brand, purolator isn't a quality brand

 

I have an older Purolator air filter, still in its box, #A44358. I use it for a day or so every year when I take my K&N out for cleaning and re-oiling. It fits the stock airbox perfectly. Is this the number on the filter you have?

 

Here's a solution to your conundrum. Return the incorrect item at the store you purchased it at. Then locate and purchase the Correct Filter for your application.
Application Guide Results

 

Get the racing beat air filter. I got it on sale for $10 plus shipping awhile ago, dont know the price now though.

 

I didn't know Racing Beat made an air filter for the stock FC airbox. I can't find it on their site; they only seem to list the K&N filter.

 

Wow, that's strange. I guess they were on sale because they stopped making them?

Its a foam like filter that you can reuse and oil. Nice piece and said racing beat on it. Glad I have one though!