No, Spyder grip frames do not fit Piranhas. The bottom of the receiver is a different shape. Mako make (or made, they've gone out of business again) two different versions - one for spyder, one for piranha. The other choices for piranhas are the Center Flag frame, or the 2002 E-force frame (the 2003 version is plastic again.) Or you could search for somebody who has upgraded their piranha and has an aluminium mechanical frame for sale.