Question: Are both Kai Hansen and Piotr Wiwczarek known for being guitarists for their respective bands?

Context paragraphs:
Necrolust: Necrolust is a demo album by the death metal band Vader released in 1989.  The cover of the album was designed by Piotr Wiwczarek.  Fenriz of Darkthrone cites this demo along with Celtic Frost's "Morbid Tales" and Bathory's "Under the Sign of the Black Mark" as key riff inspirations for "Panzerfaust".

Piotr Wiwczarek: Piotr Wiwczarek (born 22 October 1965 in Olsztyn, Poland), also known as Peter, (ex nickname Behemoth) is a Polish guitarist and vocalist who is the frontman for the death metal band Vader, as the only constant member of the band since its inception.  He has also collaborated with Kazimierz "Para" Paraszczuk on his tribute album, Bandid Rockin', and is the producer of several of Vader's releases.  He is also the founder and guitarist of a side-project, named Panzer X.

Keeper of the Seven Keys: Part I: Keeper of the Seven Keys: Part I is the second studio album by German power metal band Helloween, released in 1987.  It marks the first appearance of vocalist Michael Kiske, and is considered the album that created the genre of European-style power metal.  Kai Hansen stepped away from doing vocal duties as he had difficulties singing and playing the guitar at the same time during the previous tour.  It was an album dominated by Hansen, due to an injury to co-guitarist Michael Weikath which prevented him from performing on much of the album. " Future World" was released as a single and a music video was made for "Halloween" but with 8 minutes omitted from the song.  The band originally planned to release "Keeper of the Seven Keys: Part I" and "" as a double album, but their record label refused, insisting that the albums be released separately.  Much later in 2010, both albums were released together with bonus tracks.

Michael Kiske: Michael Kiske (born January 24, 1968) is a German singer best known as the lead vocalist for the German power metal band Helloween.  After his departure from the band, Kiske recorded four solo albums, participated on various metal and rock related projects, such as Avantasia, Place Vendome and Kiske/Somerville, while he also performed with numerous bands as a guest vocalist.  In late 2009, he formed the hard rock / heavy metal band Unisonic and began touring again after 17 years of absence.  On November 14, 2016 it was officially announced that Kiske will tour again with Helloween and Kai Hansen in 2017 and 2018.

Land of the Free (Gamma Ray album): Land of the Free is the fourth studio album by German power metal band Gamma Ray, released in 1995.  Continuing a trend that would conclude with the band's fifth studio release, the lineup for the album was different from the previous one, as "Land of the Free" was the first Gamma Ray album to be released since the departure of Ralf Scheepers, leaving Kai Hansen to take up lead vocals.  While not his first stint as a vocalist (Hansen had sung lead for Helloween until 1987 and had also recorded lead vocals on "Heal Me" from "Insanity and Genius"), it would be the first time he had performed lead vocals exclusively in 8 years.

Winds of Creation: Winds of Creation is the debut studio album by Polish death metal band Decapitated.  It was released through Earache Records subsidiary Wicked World on 11 April 2000.  The album was produced by Piotr Wiwczarek (aka Peter), from Polish death metal band Vader.

Gamma Ray (band): Gamma Ray is a power metal band from Hamburg, northern Germany, founded and fronted by Kai Hansen after his departure from the German power metal band Helloween.  Hansen is the current lead vocalist, guitarist as well as the chief songwriter of Gamma Ray.  The band is known as one of the most prominent bands of the German heavy metal scene.

Vader (band): Vader is a Polish death metal band from Olsztyn.  Formed in 1983, the group was founded by then-bassist Piotr "Peter" Wiwczarek and guitarist Zbigniew "Vika" Wróblewski.  Vader went through several lineup changes over the years, with Wiwczarek as the only constant member.  Since 2011, the band has comprised Wiwczarek on guitars and vocals, guitarist Marek "Spider" Pająk, bassist Tomasz "Hal" Halicki, and British drummer James Stewart.

Kai Hansen: Kai Michael Hansen (born 17 January 1963) is a heavy metal guitarist and vocalist.

Helloween: Helloween is a German power metal band founded in 1984 in Hamburg, Northern Germany by members of bands Iron Fist and Gentry.  Its first line-up consisted of singer and guitarist Kai Hansen, bass guitarist Markus Grosskopf, guitarist Michael Weikath, and drummer Ingo Schwichtenberg.  After the release of a self-titled EP and their debut album "Walls of Jericho" in 1985, it expanded into a quintet with the addition of singer Michael Kiske, Hansen choosing to focus on guitar instead.  Under this line-up, they released the "Keeper of the Seven Keys" albums (1987 and 1988), which established Helloween as a notable heavy metal band and led to the creation of the power metal subgenre.  However, Hansen left the band quickly after the release of "Part II" and was replaced by Roland Grapow.  He then created the band Gamma Ray.

Supporting paragraphs: Kai Hansen Piotr Wiwczarek
Answer: yes