A couple of people will tell you that over 300hp and you might have problems but it seems to be the luck of the draw dude I think 5th and 3rd tend to be problems with these boxes but again its all about the luck of the draw, some people have no problems, others (including me) have there are other options available if you wana run big power without worrying about you box, but it comes in the form of a 3k gear set from zisco