George, I like the Discovery but prefer the mouthpiece on my SCX and Easttop. Would the Xpression mouthpiece bolt onto my Discovery? If I knew for sure it would, then I would be very tempted to get the Xpression and use the Discovery for spare parts. Also, are you going to SPAH next month? I live 20 miles from St. Louis and go to SPAH when it's there.