How Much Does Your PREMAF Shot Peak on the initial hit, and what shot are you running????

For a quick example on what I'm asking...say you are running at 12.0:1 a/f ratio, and than you spray a 150 shot...What does your a/f peak to before it levels out??? How much leaner does it get???

Please let me know what shot you are running, and this is for PRE maf shots only, controlled BY THE MAF.

Thanks a lot for everyones help!

Steve