So I am running a game and the party currently has a YT-1760, I am not sure if that is actually in the books or if it is a fan creation, but the speed of it is typically a 4 in all the stuff I have seen so far. And right now the players are thinking of upgrading their smuggling ship to a speed of 5 with some engine mods. Now that is a good idea, it would be a very hard to catch ship, but the problem I am currently running into is they've already chosen to disengage completely from several space fights. Normally that is fine, but if they get the ship up to a speed 5 that means that the TIE fighters they keep running into will not be able to catch them.
I am concerned that having a smuggling freighter that fast would trivialize space combat and/or make patrol and custom ships totally irrelevant since they could fly off at max speed.
I am looking for ideas to make sure that giving them a speed 5 freighter won't make space aspects of the game inconsequential to them.