The Leopards were first to claim a place in the Wembley play-off finals on the first weekend in May, by beating eighth-placed Leicester City Riders 130-122 at the Granby Halls on Saturday and by 114-105 at the London Arena last night.
Mims has taken "Route 66" to the title with a full hand of five Americans and is glad that club owners have adopted the same format for the 1997- 98 season.
"It's the right decision and it could be necessary for another couple of seasons," Mims said.
"There just aren't enough top quality English players to go round. As long as there is a salary cap, the likes of Steve Bucknall and John Amaechi [currently playing in Greece] won't play in this League."
Leopards' John White, with 43 points in the first game, and team-mate Ed Burks, with 34 last night, rose above two foul- riddled encounters which featured well over 120 free throws.
Chester Jets took the edge on reaching a Wembley semi-final against Leopards by beating last season's play-off winners, Birmingham Bullets, 86-78 last night in their first game of the best-of-three series.
The season's biggest crowd of over 11,000 saw sixth-placed Manchester Giants waste home advantage by losing 77-72 to Sheffield Sharks. London Towers opened their series against the Eagles with a 91-79 victory in Newcastle on Friday.Reuse content