The Omni has a nose angle of 17 deg, so you need some low-angle trucks. Get either the Randal 35* or the Gullwing Bombers, whichever you think is prettier.
but first things first, OMNI doesnt make a drop-thru... its a lowered board...
2nd thing. Buy some grizzleys, fuck the rest of that shit off grizzleys are primo trucks for DH. No point in arguing that. Only reason i havent been talking em up before is coz there was no stock mwahaha...
3rd thing. OMNIs are out of stock so look for another deck buddy...
4th thing. ENOUGH WITH THESE FUCKING THREADS!!! There has got to be 70,000,000 fucken threads with people going "duh, which twucks and board should i be buying" and yes thats TWUCKS coz you sound like an idiot. Go and look at every 2nd thread there is all the information right there coz you grommets just cant make up your fucken minds... fuck... Buy what ever looks pretty and whatever costs the least. chances are you havent tried anything else so whatever you buy will be good, you dont have the experience to tell which set-up is better, that comes with time (and money)