I had Silverstar zXe for lows and preferred them to the ultras ... the best halogen bulbs for highs by a mile are the Toshiba HIR 9011, but they are almost impossible to find as they stopped manufacturing them. The only 9011 HIRs left are made by Philips and are nowhere near as good as the original Toshiba, but still better than the Silverstars for highs.