Here's why:
* Stock Power Difference: The Magnum RT boasts a significantly more powerful Hemi V8 engine compared to the Impala SS's LT1 V8. While modifications to the Impala SS increase horsepower, they are unlikely to bridge the considerable gap in factory power.
* Weight: While the Impala SS is not excessively heavy, the Magnum RT might be slightly lighter, depending on options. A lighter weight for similar power translates to a quicker time.
* Transmission and Drivetrain: The Magnum's transmission and drivetrain are likely more modern and efficient, offering better power delivery.
* Aerodynamics: Although not a massive factor at a quarter-mile, the Magnum's slightly more aerodynamic shape could provide a tiny edge.
The Impala's modifications help, but they're unlikely to overcome the inherent power advantage of the Magnum RT. The quarter-mile is a test of raw power and acceleration, and the Magnum starts with a substantial advantage.