What's he doing? For time attack, where you only care about 1 or 2 hotlaps, stock radiator might be fine, especially if he lives up north. If he lives down south like me, Summer months will give him problems on heat. Mishimoto X-line, Koyo, and CBRD are his only decent options, with CBRD regarded as providing the best cooling. He should have no problems with a cbrd in any temp at any power level. Also be sure he's running the proper mix (or just pure water + wetter).
Either way, he won't blow up as long as he watches his gauge. Just pull back once temps start rising.