It is so simple ,if you firewall a B737NG the thrust produced will be the max rated that you bought as shown on the CDU IDENT page subject to outside atmospheric conditions.
If you have a 22k engine the most you will get is 22700lbs as the EEC will use a fuel schedule to govern N1 speed to produce a N1 speed that equates to 22700lbs.
This max speed of N1 may be reached prior to the thrust lever reaching the cockpit fwd stop but the EEC will not schedule any more fuel,therefore you will not gain any more thrust with further thrust lever movement.