How fast with stock airbox intake and k&n panel filter !

I can tell you for a fact that a drop-in K&N panel filter will work better on a Mass-Air controlled Fox than a cone filter under the hood. The turbulance from the fan screws with the MAF sensor's readings and makes it lurch a bit at low speeds and idle, and you're just sucking hot air from underhood, whereas the stock airbox pulls air from in the fender and the MAF is designed to work specifically with that airbox in front of it.

You could opt for a fenderwell-mounted cone filter, but don't expect any more gains, realistically, over a stock airbox w/K&N panel filter unless you've got one seriously built-up motor to really make use of it ... and even then, you run into issues with that elbow ahead of the MAF sometimes requiring you to "clock" (rotate) the MAF sensor so it doesn't get weird airflow readings.

I spent a while looking at intakes for the 5.0 i noticed that Mac, BBK, and i think AEM all made CAI systems for it but K&N didnt. I decided to email them about it and a while later i got a response saying that it's most likely because there was very little or no performance gain from the product. so im assuming that the stock airboxes are pretty efficient for most setups

Steeda site used to recommend a K&N with stock system up to 350HP

I went from a cone filter mounted at the end with a C&L pipe to a stock air box with a K&N. Now I have my IAT monted in the pipe to get more accurate readings and I noticed about a 20 degree lower air temps just from that. I am a firm believer. Noticed quite a bit more response as well and the car was a ton smoother. So yes, stock air box works quite well.

Wow good to know. I was about to drop $150 on a cone filter system.

If you still have the stock tubing the C&L true flow with the stock air box/k&n work quite well together. You might have 130 for brand new parts and be better off than a maf mounted air filter.