According to the plugs the car was already running a tad rich before I pulled the air cleaner, so I shouldn't have had to jet up much. Did I try jetting up with it off? Nope, I didn't, and that is because I am a firm believer in getting clean air into my engine...I'll lose a tenth or two (or in my case slow down a tenth) to keep only clean air in my engine....I've heard of WAY too many scenarios that went sour with an air cleaner off and LOTS of people who gained or lost nothing without an air cleaner compared to with one for me to run without it all the time.

Just my personal preference