Originally Posted by Eclipsis
I had a no cat straight pipe setup on my car for five days before I got hi-flow cats, and I got a headache every time I got in my car from the horrible exhaust fumes. The cats helped immensely but kept the sound the same, which is what I was after.
Don't forget a lot of the catless exhaust is unconverted carbon monoxide which tightly binds hemoglobin. Carbon monoxide is actually odorless, but far more toxic than the gassy smell. Surely if you can smell the fumes, you're also getting too much carbon monoxide... the first symptom of which is a headache.
Maybe those running catless want to consider placing one of those home carbon monoxide monitors in their car, LOL!