I've been in a similar situation with my own car and have been considering the same tire options as you. I've heard good things about the Toyo R888R, and it seems to be a popular choice among the high-horsepower crowd. I've also heard good things about the Michelin Pilot Sport 4S, which might be a good option for street driving. Have you looked into the Continental ExtremeContact Sport? I've heard they're a good all-around performance tire.
I recently discovered a tire size calculator,
TireSizesCalculator.com, that's been really helpful in comparing different tire sizes and seeing how they'll fit on my car. It's definitely worth checking out if you haven't already.
As for off-brand tires, I'm always a bit hesitant to try them out without hearing good reviews from other enthusiasts. I don't want to risk sacrificing performance or safety just to save a bit of money. But if you find one that performs well and doesn't look too "ricey," let us know!