The BMI TC3 chassis was the first aftermarket chassis I ever purchased. It was a big help with my TC3. I made the TC3 easier to work on, more balanced, and definately better for carpet with the increased stiffness. The motor mount was also a huge improvement over the stock "cam" mount mechanism.
I will agree with the others and go with the BMI. The chassis is thick, rigid, and the overall weight is lighter than the Factory Team setup. The TC3 with the BMI and the right setup will be as quick as any new kit on the market. Its the best $119.00 you can spend on your car (aside from a good servo).