Congrats on the skid plate. Between the loss of low-end torque and NON-filtering ability of the K&N, you'll see why you got it so cheap. You'll actually see a huge difference in the color of your oil (in the same mileage interval) with the K&N compared to the stock filter.
Yes, bad. I tow snowmobiles in an enclosed trailer in the winter and had to go back to the stock setup. Night and day difference. Alot of people associate noise with power. You may see a difference in the 4-5000 rpm range with the K&N but you are not at that rpm constantly when towing.
If you want to feel a difference buy some good headers and replace your factory muffler with a 2 1/2 freeflowing muffler like a Magnaflow and keep the stock 2 1/4" piping.