I have a 1989 4.3 l MCM V6 175 hp alpha one. I am planning to replace the 2 bbl Mercarb with a Edelbrock 1409 carb. Of course, I will have to replace the intake manifold and am going to use the Edelbrock Performer. Will I get any performance gains from an aftermarket exhaust manifold? they claim lower resistance, increased horsepower, etc