First of all, you guys cleaning your K&N filters every 2 oil changes are wasting alot of money on those recharger kits. K&N recommends cleaning them\reoiling them every 40-50k miles unless you live in a very dusty climate. They advertise that they actually flow better when "somewhat dirty" so your cutting down on airflow by recharging them all the time.
You WILL gain power at full throttle with a K&N filter if your engine can benifit from more available air. Meaning, if your paper filter flows less than your engine throttle body can swallow, you will gain power with the higher flowing K&N filters. You will get different results for different vehicles.
Also, your going to gain more from a complete "cold air intake" system than you will from a K&N panel filter. Why? Because even after the better flowing K&N panel filter takes in more air it still has to bounce around the restrictive airbox and into the ribbed (turbulent) air duct that leads to the throttle body. If you replace the system with a smooth path to the throttle body you will better benifit from the increased K&N air flow.
I had the Thrasher system and it gave me a nice power improvement over stock. My ss fenderwell intake (completely smooth shot to the throttle body) with a 9 inch K&N cone was a massive improvement even over the Thrasher system, likely because of the removal of the ribbed "air duct".