UMUR "Mutant Supremacy" is the third demo release by US, Buffalo, New York based thrash metal act Tirant Sin. The demo was independently released in 1988. It´s the successor to the October 1987 demo "Chaotic Destruction" and there´s been one lineup change since the predecessor as lead vocalist Dennis John Glinski has been replaced by Chris Barnes. Barnes was actually a founding member of Tirant Sin, but he was only shortly in the band in 1985.

The addition of Barnes to the lineup means that "Mutant Supremacy" features three future members of Cannibal Corpse in the lineup in Barnes, Paul Mazurkiewicz (drums) and Bob Rusay (guitars). Tirant Sin would soon fold and along with some members of fellow Buffalo thrash metal act Beyond Death, the three above mentioned members of Tirant Sin would form Cannibal Corpse.

Stylistically there´s nothing on "Mutant Supremacy" which points in the direction of death metal though, as this is through and through aggressive and brutal thrash metal, just as the band also played on the first two demos. Barnes performs screaming throaty vocals which are completely different from the growling vocals he would start performing just a year down the line.

The sound production on the demo is raw and unpolished but it´s decent enough and you´re able to hear all details. Just as the case was on the first two demos the songwriting is what holds Tirant Sin back. It´s not awful or anything like that, but it´s very standard for the genre, and the tracks aren´t particularly memorable. A 2.5 - 3 star (55%) rating is warranted.