Originally Posted by Rui Z

I would agree with you about the exhaust leak being bad if you were running HFC's or test pipes. But I believe the people who are doing the washer mod all have stock catalytic converters. All modern catalytic converters (our 370Z is a LEVII-ULEV cars which emit < 1.7 grams of CO/mile) convert carbon monoxide to carbon dioxide so efficiently that it will not kill you while driving if a portion of the fumes were to leak into the car. There have been a significant drop in carbon monoxide suicides from car fumes because of the more efficient cats.

People are not stupid for doing the washer mod on here. Just don't do it with HFC's, and especially not with test pipes.