Which string have you used that are closest in feel, performance and sound to the BG66UM ? Have tried Bg85, NG95, NG99, bg68ti, none comes close. Currently have Bg66UM and NG99 on 2 identical racket (Bs11 4UG5). The Bg66UM gives me much better control and feel than the 99. Agree BG66UM loses tension rather quickly. But focus on fresh vs fresh if I can.