I own a Cinepro 3k6 amplifier that puts out 350 watts per channel. The 80Ti's, VP150 & QS-8 surrounds are all rated at 400 Watts Max power. My amplifier rating is into 8 ohms, so I'm wondering if I still have to be careful of overpowering these speakers? I don't ever expect to have them that loud, but I was just wondering how cautious I need to be?

The odds of you having any problem falls between zero and nil. Even though the products are rated at 4 ohms, they are an extremely stable 4 ohms by industry standards. Very small, inexpensive receivers is really the only category of amplification that might make stability an issue.

I wasn't worried about my amplifiers ability with the 4 ohm load. I was just wondering how careful I needed to be of overpowering the speakers and damaging them due to excess wattage (ie.: Speaker rated at max power 400 watts {continuous?} at 4 ohms vs. Amplifier rated at 350 watts per channel into 8 ohms)?