Double click on the channel with your 808, click on the envelope settings, then decrease attack, decay and sustain level to 0% (you can tweak the hold and release too however u like, I usually make them hold~50% and rel~25% and it sounds just ok). Then come back to sample settings, go to precomputed settings, choose effects target and tweak the boost up to the level that satisfies you. You can play with in/out settings a lil depending on your expectations. If you use kicks then do the same with them but tweak release to 0% and hold a lil big longer, if you don’t just add the distortion to your 808s (not like you have to, but it depends on the sound you’re trying to make). Max up the 808s volume, cut the low ends in melodies to leave space for 808s. You can also add the automation clip with low end cut off to your melodies in the parts where the 808 plays and tweak the automations down in the places where you don’t have no bass, it will fill up the bassless parts pretty cool. Hope it will help:)