I have 305 lg4 camaro.I have found a direct fit high flow converter for this application. It has advertised horse gains of 8 to 10 hp and 12 pounds of torque. It is not a random Tech which flows at 382 cfm but is dead comparable in numbers and at half the price. Can I get this gain in a stock cat swap alone? I do plan on getting a quality cat back system at the same time. What kind of assumable hp and torque in combination can I expect?