We've got a couple of these here at work:
http://www.nhresearch.com/Products/4...onic-load.html
I've run tests on some of our power systems to 10kW peaks with 2 of these paralleled (up to 36kW capable with 6 in parallel). For any real high power testing, a consumer oriented load just isn't going to get you there IMO. For instance, if you want to run a steady state load of 30A and then peak it to 150A for 10mS, this will do it with ease.