2. The pistons used in the old version of this engine were never meant for a forced-induction application. Although they were machined from a quality forging, there are areas in the piston design that need changing in order to survive a big shot of gas. On the left is one of the old pistons. Notice the skirt depth is much greater than the new piston on the right. CP shortened the piston skirt to keep as much of it in the cylinder at bottom dead center of the stroke as possible. This keeps the piston from rocking in the bore too much and side-loading the skirt. The barrel shape of the nitrous piston is also different. It's not round, its an ovoid shape that's meant to expand under heat without sticking in the bore.