NPC (I think it's Nick's Perfomance Clutches in Qld) make a custom flywheel/clutch combo for big horsepower 4AGTE's. Pretty sure it's a cromoly flywheel and some sort of custom clutch that is meant to be far better in clamping than the toyota style pressure plate can be.
I have heard of a few other flywheel manufacturers for the 4A over the years but can't remember the names. TODA springs to mind (I could be wrong though?).