It sounds like your goal is to beat your friend in his C63. I'm guessing his C63 has around 550bhp, or a bit under...?
There's more to beating a car than comparing manufacturer's bhp figures. Engines usually lose bhp with age. Consider the weight, torque, 0-60 times etc if beating a C63 is your real goal, and factor in losses over time.
I applaud your plan to get the handling tip-top, that's good. Unfortunately it's not glamorous: most aftermarket obvious bits don't improve the handling. Over the years, not much knicker elastic has been snapped by viewing new OEM suspension trailing arms.
What will you do if your friend sells the C63 for a 1.8 Mondeo? Your supra's raison d'etre has vanished.
I know I sound like the forum grandad, I'm just prompting you to consider what you want out of it, so that you're more likely to enjoy it and it not be a flash in the pan. No problem if you want a wide-bodied monster with rock-hard suspension, there's several people on here that share this view, just don't expect it to always improve the performance.