My car ran 11.53@118 with a 6.5" K&N on a screenless LT1 MAF stuffed into the stock airbox.
It runs and idles better than it ever did with any plastic MAF, including two GM originals.
Take a dremel to the screen ridge and the MAF will flow over 100 CFM more than it does with the screen in place. A K&N with a good throat venturi does a pretty good job of straightening the flow into the MAF, without restricting the flow.
There are K&N's that have really crappy, squared off throats inside. Those won't do the flow into the MAF any good.