In honesty, the water cooling system radiator shouldn't really need an upgrade with the extra power, as long as your oil temperatures are kept under control with an appropriately sized oil cooler, that'll keep the strain off the water cooling system, the amount of extra cooling the water cooling system does is fairly minimal compared to the oil system, it's just that you usually see the heat coming from the oil being dumped into the water, which then can't cope.
You usually see issues when the oil starts to get excessively hot, which then passes that heat via the oil-water heat exchanger (note I say exchanger, not cooler, it's purpose is two fold, to warm the oil during the warmup phase and to cool the oil during normal running) which isn't designed to take the amount of heat you're putting into it. The main thing to make sure is that your intercooler isn't covering the core too much or there's gaps at the edges that are allowing the cooling air to just pass around the edges and to install an oil cooler with thermostatic plate.
You usually see issues when the oil starts to get excessively hot, which then passes that heat via the oil-water heat exchanger (note I say exchanger, not cooler, it's purpose is two fold, to warm the oil during the warmup phase and to cool the oil during normal running) which isn't designed to take the amount of heat you're putting into it. The main thing to make sure is that your intercooler isn't covering the core too much or there's gaps at the edges that are allowing the cooling air to just pass around the edges and to install an oil cooler with thermostatic plate.
