400 whp would be as high as I'd go. Anything after that for a daily driver is a bit overkill. Lap3 USA, Vivid Racing, and GAN Tuning have ECU tuning options that can give the G70 and extra kick in power.
When setting out to rival one of the best luxury compact sedans the industry has always known, understanding the fundamental characteristics that make up it's winning formula and building on that becomes the only way to compete, especially for an underdog like Genesis. One of those...