MZR LF is the 2.0L, biggest thing you can drop in to STL. in a protege (strut front) or 3 (strut front I think) it's a 2633# car, in a 6 it's 2700# (SLA front).

yeah, brakes are possibly an issue for the heavy cars, relatively speaking, but frankly maxed brakes on a light car with DOT tires of a max 225 section means you probobly have more brake than you can use - so there's likely a middle ground.