b303 is a decent cam, it is bigger than stock....if i remember right the e303 is more emissions friendly
B303
Duration'': 224°/224° @ .050''
Lift: .480''/.480''
Trans: 5-Speed
Notes: Fair Idle, Good Low-End Torque, Significant Top-End Power Above 4,000 RPM
a stock cam is only .444/.444
E303
Duration: 220°/220° @ .050''
Lift: .498''/.498''
Trans: 5-Speed/Automatic, Emissions Legal (E.O.#D-225-16) with 5-Speed
Notes: Good Idle, Excellent Low- and Mid Range Torque, Great for Superchargers.