You can see on the recorded results, a 1200 rpm gain, a 12.5 hp gain and 4.8 ft/lbs torque gain but more importantly the HP peak moved into a higher rpm rang and the torque curve became stronger at lower rpm with a broader curve spread out over a wide rpm range.
All in all, forget going cheep, you will only pay with increased gas mileage and less power with dryer duct. Your don't need silicone rubber, that's for turbo and high heat, the black rubber is all you need. here is the best deal.