I am using crossfire 68/3000 tanks and the fps is +/- 2 in variation using slamball/starball and Jav. barrel.
I felt zip reason to spend more $$$ as the sidewinder is a great hpr! Also no shootdown when getting on the trigger.
BUT have had leak problems with the fill nipple that came on the 2 that I am using, but no problems with the new ones since.