well i just chnaged it to a 300zx NA filter. when i rev it upon start up, the filter whistles. it will whistle to anything that i havent revved it up to. say i rev my engine to 3 k, it will whsitle and any reving to 3 k afterwards the first rev it wont whistle at all. but say i decide to rev it to 5 k, then it will whistle from 3k to 5k. any ideas?

 

is it pretty loud? or just little noise in the background

 

sorry this is offtopic, I was wondering did the fuel filter affect your gas mileage?

 

not loud but noticeable. mileage is about the same. i shift at 2500 or 3k for accel. once at speed i usualy shift up and try to keep revs under 2k > poor college student