Hello everyone! I'm new to this page and I myself own a pontiac G8 V6. I was reading your thread and as far as building a more durable transmission, there is a 5L40E performance transmission set you can buy from level 10. It cost $5K that comes with a new transmission that can handle 700hp upward to 1000hp, wires and torque converter. Pricy? Yes, but instead of buy a new one or rebuilding I think it might be worth the money and I do believe it comes with a warranty. Just something worth looking at if you really want to push it to the limit. With all the mods I have in mind including engine mods I found that will beef up the engine, you could get 600hp-800hp depending on what route you go as far as force induction. They've shown it can run 444hp naturally aspirated but that's not with all the mods however.