One of the first things we hear Pilot say in the first episode of the show is [D'argo ripping the bits out of the control console to remove Moya's slave collar caused damage ] "Leading to our current top speed, which is barely hetch 2." So through...whatever means Moya can propel herself at "hetch" speeds, usually in excess of "2" but that leviathans are also capable of a unique thing called a starburst. Which depending on the episode is either an instantaneous experience or a state the ship spends at least a little time in.

Again, Farscape is extremely soft sci-fi. Rigel somehow farts helium. He doesn't eat food that contains a lot of helium, yet he farts helium. That's the approach to science taken by Farscape. There's more than a little actual magic in the show. It's a show mainly about its characters and how they cope with (usually ridiculous) situations.

Moya could travel at Hetch 9 The Locket. She was faster than a Marauder (Hetch 7) and only slightly slower than a full Command Carrier.

Starburst was actually travel through another dimension of space. Self Inflicted Wounds

only trek and sg1 try to explain it in a scifi/pseudorelistic way, all others avoid, because they dont want to have to explain in a real way that would have to add real science to the discussion. BSG avoids it altogether, somehow the series, the humans and cylons suddenly had the tech out of the blue.