One of the problems with the Tri-Stat rules as written is that they use a roll-under dice mechanic. There's nothing wrong with that as such. Games like BRP, Hero System, and Thousand Suns use roll under mechanics to good effect. The thing is that in BESM/Tri-Stat it isn't implemented well.
For Tri-Stat d6 take the example of two average people, each with Stats of 4 and no Attributes, Defects or Skills. Each will have an Attack Combat Value of 4 and a Defence Combat Value of 2. That means that if they get into a fight they will only have a one in six chance of hitting each other and only a three percent chance of defending themselves. Not only couldn't they fight worth a damn, they'd be terrible at darts.
Now, reverse things so that instead of rolling under four (or two!) on 2d6 they roll the dice and add their Stat to the total. Suddenly things play out very differently. There's no more flailing around, and one of them will be successful each round. Plus characters can have superhuman stats and still just roll 2d6 instead of switching to 2d10, 2d12 or whatever. Not surprisingly Mark switched to this mechanic for the BESM 3rd edition rules.
In most cases rolling high will involve opposed rolls between two characters, but for situations where a player is making a skill roll to accomplish a task (e.g., repairing something, climbing something, etc.) here's a list of target numbers to use. The Easy, Average, or Difficult TN's, will be used most often, but others are listed for extreme circumstances or superhuman games. For cinematic games I'd also use the Tunnels & Trolls rule of DARO, doubles add and roll over. That way there's always a chance for the characters to accomplish the impossible.
Tri-Stat d6 House Rules:
Optional Cinematic Rule: DARO, doubles add and roll over.
If you roll doubles, add that number and roll again until you don’t roll doubles.