I’m looking at buying a Silber turbo and I wanted to be educated on the system before I talk to the guy so I don’t waste his time. It’s on a 850 patriot. I want to run pump gas half the time and a little avgas some of the time. I believe to run pump gas at my elevation (riding at about 6000 and a little bit of playing in a field around 3000) I would run the 5 pound spring and a with a little avgas I can run the 7 pound spring. Is this right? If I change the weights between the two do I need to change clutching?