Z.Z. Top, that low-down and dirty band of Texas chili rockers, has had a change of heart, or image, at any rate. They've kept their long, straggly beards and Wild West chapeaux; but at their show last night at the Capital Centre, they strode about the stage littered with "Alien"-like space gear, with fireworks and lasers shooting off in all directions -- a kind of Doc Holiday Rock Meets the Beast of Saturn.

While the Toppers have changed their act, they have, regrettably, failed to change their tune. Their performance was a mega-decibled display of the blues-bsed, heavy-metal music that has always been their trademark. It is tempting to ponder how three musicians, playing just rudimentary riffs and repetitive material could possible sustain, musically, an entire show. The answer is quite simple -- they don't.

What Z.Z. Top does manage, however, is a witty and self-deprecating performance filled with imaginative gimmicks (such as cheap sunglasses) and riotous monologues. Though Billy Gibbons borrowed his guitar style from the '60s British bluesers, his gregarious and comically deranged persona is all his own.His interminable solos, accompanied by Dusty Hill's gurgling base and Frank Beard's ponderous percussion, quickly became monotonous, but the group survived on sheer energy and down-home chutzpah.

Z.Z. Top might be a sound for sore ears, but they are also a joy to behold.