The rest of the tweaks should do the job without touch in the build.prop. So you should check the improve in performence even if the /system/build.prop is untouched.
Some codes in the build.prop could have unexpected results, so its better don't touch there. And, becouse of that, the tweak doesn't change it...
You can, however, add the codes by yourself or running the .sh script.
But do a backup before.