If the temp goes much above your thermostat's rating, you need better cooling system. Maybe not a larger radiator, but think about airflow (radiator blocked by intercoolers, sheet metal, etc?) and fan. A lot of electric fan setups are poor, the stock engine driven fan is fine for a non-boosted engine. Or maybe a better radiator. The stock one cools a stock or moderately built engine just fine unless it is partially corroded inside or out.