The FDL has had a lot of changes over the years.
First it was given a bigger power plant, and then epic cooling abilities.
Then the cooling got nerfed.
Personally, I think the power plant should be reduced back to original, now we have engineering, and it's heat efficiency increased a small amount.
Then, give it a larger fuel tank, and a larger FSD, if possible.
This would then actually slot it in to the bounty hunter role, by being able to actually chase targets for more than 3 jumps.
By my calculations (using coriolis. Lol)
If the FDL was given a Class 5 power plant (-1), and class 5 FSD (+1), and a Class 4 fuel tank.
A fairly full battle setup could still only jump 25~ly without engineering. Or 37.5~ly with a 50% roll.
But it would have to have a heavily engineered power plant to support all the modules, shield boosters, etc. Which means it's heat efficiency would tank.
This FDL, using just stats to artificially raise the jump range to a 5A FSD, can do 23ly, or 34.5~ly, in a good battle setup.
It's still not going to catch any engineered explorers, but it'll be able to keep up with most other ships.
It doesn't take in to account the added fuel from a 4C 16t tank though.
CMDR Cosmic Spacehead