Ok getting back into rc after a long break. I have a novarossi keepoff 21-7XL with 9901 pipe and4102 header new. Going in a mbx7tr. Questions how do the keepoff like to tune anything special? Also I have a square 4105 header. Which would be better? Looking for smooth and fuel mileage. Also my friend that sold me the motor has 5.4 carb venturi in it. I have some old nova carb venturi. From when I use to run a plus4t.sizes 7.0 7.5 8.0 Are they the same for this carb and what size should I run? And finally plugs. Is the C6 still best to use. Any help I would appreciate it. Nobody runs nova at my local track anymore. But i use to only run nova. So that's why I came back to nova. One last thing. How bad does a dented up pipe affect performance. I have a old 9853. In rough shape but i remember it use to make my plus 4s run really good.