OK since no one is saying anything I will let it out and join all of you guys in the Sith
If you want more renown but you don't want to cheat you can alter your realism settings. That means you can play in any realism level you like and still get full renown for the ships you kill. That way at least you do 'earn' the renown
To do this you have to edit the GameplaySettings.cfg file at C\Program Files\Ubisoft\SH3\data\Cfg To do this go towards the end of the file where it say [Realism Settings]. There set every realism setting you're not using to zero and add more value to the ones you're using. Be careful though as all the numbers should add to 100. That way you're playing at 100% realism for the computer and you get full renown.
Now can I have my place in Sith:p