Portal mod is pretty cool, but know that you can also "Hack" (temper) with replays.
With this technique, you can make an object or a tori teleport or go extremely fast, jump extremely high, etc...
It's pretty hard to do though,
here's a beginner guide, and
here's a script that might make it a little easier for you.
I think this kinda post would also be more appropriated in the
suggest a script board !
Good luck !