I recently installed a K&N drop in air filter in my 08 civic, it seems to definitely help the acceleration. Has anybody had problems running a K&N filter in their civics?

 

Not that I know of. K&N is a reputable brand name.

 

Agreed. You should be fine using it. The only advice I'll pass along is that when you decide to wash it, let it air dry. When you're ready to oil it, keep in mind that the oil is dyed red, so it'll seep through the filter and onto whatever is underneath, so don't do it on the kitchen counter (no need to ask me how I know). Also, don't over-oil it.