A boost for Hattrick clubs existed during the earlier seasons of Hattrick. New clubs in "underrepresented" leagues would receive 1500 supporters as well as a "super player". With average skill levels significantly lower than they are now, the "super player" could be used to produce early on-field success or could be sold for an immediate windfall (potentially, 1 000 000 €). Additionally, the 1500 supporters would immediately lead to larger crowds and greater income from attendance.
The boost program was modified (eliminating the bonus in the USA) in April of 2002 (official announcement). Clubs that were formed after the program ended are sometimes referred to as "post-boost" clubs.
It's impossible to say how much of an advantage this provided to clubs receiving it, over and above the inherent advantage they already had from an early start in the game. Through season 30, only two post-boost clubs (RH Crew and Stiinta United) had ascended to the Major League. However, in the following seasons, a number of long-tenured sides left the top flight, and by season 35, there was only one boost club (Rizzo's Salesmen) in the Major League.