Catscan played a showcase with "5 mad punk bands" at nationally renowned Jammin' Java, a snooty proto-hipster coffee shop, on October 9th, 2003. This opportunity came through mentor Jon Carroll, who joined Catscan on stage for a live rendition of Carroll's Living in an Insane Asylum. This performance also featured David Shelby who had co-written the song with Jon years before. The headlining act, Further From, shared their drum set and guitar with Catscan- who's own equipment broke just before and during their performance. The band thanked their gracious hosts by informing the audience that the show was over and to "go home" just before the headlining act took the stage. Due to this faux-pas, Catscan never heard from Further From, or Jammin’ Java, ever again.
A few new compositions from their yet-to-be-recorded next album were field tested at the Jammin' Java show as well as their second Battle of the Bands at James Madison High School. The following week, Catscan played another Battle at the school’s after prom party, although they were too young to have actually attended the prom itself. They won second place, one hundred dollars, and a free VHS of themselves lip-syncing to Welcome to the Jungle.
Paul was sent off to a prestigious music and arts camp in Michigan that summer of 2004 to study euphonium. Catscan was put on a temporary hiatus, leaving Mason to explore a few other musical ventures. He started a new band with Eric Randall and Khai Phan, a satirical screamo group called Fallen August. Their tongue-in-cheek sarcastic emo music gained them much MySpace fandom, as well as several uncomfortably awkward gigs. Mason and Jay also wrote and recorded an EP called The Romans without Paul and mailed it to him at Interlochen. Shortly after Paul's triumphant return, the band recorded Based on a Fake Story, perhaps their first true classic. Mason, Paul, and Jay put almost a year's worth of effort in writing, practicing, and recording, a radical change from their rougher and more spontaneous recording style.
Catscan started a new tradition of annual holiday extravaganzas with 2005's Christmas on the Planet of the Apes show in Mason's basement, which featured the first appearance by Santa Ape. Because it lacked the technical and performance issues of all their prior gigs, the band felt that this was their first well-received show. Many who attended the show as classmates and friends of the group, left as fans.
The band briefly recruited Drew Gingras, a talented young guitarist, in late 2005, enabling Mason to concentrate more on keyboards and adding another layer to the band's live sound. However, Drew's external obligations to other bands left him under prepared for his first and only performance with Catscan, who decided to revert back to a trio, parting amiably with their friend. While recording their follow-up to Based on a Fake Story, Catscan also grew interested in video and visual media. They filmed several music videos for both Catscan and Fallen August as well as including the experimental horror film, Midgetville with members of the Project Grapefruit Collective.
William Henry Harrison came out at the end of their high school careers. This album felt much darker than any of their previous works. Paul's unavailability gave Mason executive control of the project, who in turn produced a much more aggressive and experimental album. Mason and Paul also recorded a live-in-studio piece called Nostradamus Predicted Hitler with Eric Randall, Khai Phan, and Jeff Smith, which was even more free-form.
Having graduated high school, and with two solid albums under their belts, Catscan began putting press kits together in order to go public. They recorded a split, Yellow Cat, with Yellow People. The two bands played many shows together and formed an indie label, Kaiju Records, for which they also recruited The Norman Rockwells, MC Stonewall Hill, and Richy&Georgie. Catscan's web presence was also gaining steam through emerging social networking avenues and their own website, developed by Marco Ceppi. Mason, Paul, and Jay started preparations for a tour of the east coast, armed with professionally shot photography of the band as well as a collection of their best material. They named this demo collection Manifest Destiny, and felt ready to conquer the music world.