You may EQ your 808 sample pack in a few different ways. If you're going to limit the 808, I propose using a highpass filter with a 150hz cut. If you want to improve the 808's low end, use a lowpass filter below 300hz. Boost about 10kHz by 10 dB for extra airiness. Boost the upper-mid frequencies like cymbals and hi-hats by 1 decibel each time from 5kHz to 10kHz until they sound in balance with everything else you've EQed so far. Instruments with persistent tones, it is widely assumed, require less EQing than those with transient tones.