The below is what i received from Bulter Parachute regarding tightening the leg straps after sitting in the cockpit.

Hello Jonathan,

It's always nice to hear from customers who take their emergency equipment serious enough to ask questions. It comes down to personal preference. Our Owner's Manual states: Tighten the leg straps until they are snug while standing erect... This adjustment will feel slightly looser after you sit in your aircraft; if desired, you may further tighten the leg straps after you are seated." Both methods will produce a fit that will be fine should you have to bailout. My personal preference is to snug the straps a little tighter after I am seat in the aircraft. A harness that is slightly tighter has no negative effects and will ensure that your harness is not too loose.. You will not fall out of a harness that is too loose, but one that is drastically too loose may cause the chest strap to contact the neck or chin on deployment. This can cause injury. You don't have to snug the straps to the point of discomfort or cutting off blood supply; just slightly tighter is fine and ensures your harness will be snug on deployment. Hope this helps.