Thomas, you can purchase a SuperTrapp Pipe from several suppliers for your King Quad. I don't know any thing about the Cobra, but I did install a S/Trapp on my KQ. As King, said,I also experienced a difference in mid to top range. But then, I installed a Dyno Jet Kit, on the carb and BAM! Now I get power at low to mid range. I have not installed a free flow air filter such as K&N or similar because I feel the engine is working fine with the stock air filter. Back to the S/Trapp, you only need to install enough disk to get the engine to breath properly. I put 8 disk in mine. I tried more and less. The more you use, the quieter. The less, the louder. The key is, you want to adjust the back pressure so the air/fuel mixture is just right for your area of elevation or where ever you're riding. If you need more info on how to contact the manufacturer or a supplier, e-mail me and I'll forward you all you need to do your own investigation on these.
Chuck, Suzuki KQ 300, GPS & lunch...