I think I may just use the stock one. It is on a Aerotech Yak. My goal for this plane is 15.5 pounds. The prototype was 16.5 with a DA on cannister and 2 flight pak batteries and aluminum tubes and gear. I save 5 oz with just the engine and can save another half pound with carbon parts. If I end up being 2 or 3 oz from 15.5, then I will probably order a thin walled stainless header from KS or something along those lines. Thanks.