In February 2006, Waltman joined MTV's newly formed Wrestling Society X (WSX) promotion, as 6-Pac. At their inaugural tapings on February 9, 6-Pac had a ten-man hardcore battle royal ladder match, which both he and Vampiro won by climbing the ladder to retrieve WSX contracts. 6-Pac lost a WSX Championship title match to Vampiro the following week. He challenged Vampiro in episode four, as a ruse to introduce Ricky Banderas, who attacked Vampiro from behind. He later defeated Human Tornado and Scorpio Sky in singles matches, and teased an affair with Lizzy Valentine (the valet and girlfriend of Matt Sydal), though WSX folded before the angle could go on any further.  Waltman, under his real name, defeated Adam Pearce for the NWA Heritage Championship in El Paso, Texas on April 21, 2007. He defended it against El Sicodelico, Jr. on April 27, and lost it to Pearce two days later. On July 8, 2007, Waltman teamed with Billy Kidman in a three-way tag match in McAllen, Texas for the NWA World Tag Team Championship, which had been vacated by Team 3D after the NWA stopped working with TNA. They lost the match to Karl Anderson and Joey Ryan.  On the May 14, 2008, episode of NWA Wrestling Showcase, Waltman challenged Pearce for the NWA World Heavyweight Championship. The match ended prematurely after Waltman legitimately injured his knee five minutes in. He was attacked by The Real American Heroes and Pearce, so won by disqualification. As wrestling titles can generally only change hands by pinfall or submission, Pearce retained the belt.

Answer this question "What other matches during this time frame?" by extracting the answer from the text above.
On the May 14, 2008, episode of NWA Wrestling Showcase, Waltman challenged Pearce for the NWA World Heavyweight Championship.