I'm just curious to know this cause I know the lexus has more hp but the mazda is smaller. I think the lexus will outperform but I'm not sure.

Obviously the Mazda 3.

The Mazda 3 has 263HP 2.3L 4 cylinder turbocharged engine.
The Lexus has a 272HP 3.5L V6 engine.

It is also much lighter, smaller, and more aerodynamic.
It also handles much better.

The 0-60mph time for the Lexus ES350 is 6.8 seconds.
Top speed is around 150mph.
The 0-60mph time for the Mazdaspeed 3 is 5.9 seconds.
Top speed is 155mph.

I would pick the Lexus. However, I haven't compared both of these cars in depth so perhaps I'd be wrong in the choice I selected here.

EDIT: Based on the latest post here, the stats may indeed favor the Mazdaspeed 3 - but not by much. Therefore, I would have to add that if you're truly going to set up a race between these 2 cars .... the winner will come down to how good each individual driver is.