If you are already at 5 gr/lb then adding weight to the bow is going to void the warranty BUT going a little light with a short draw should not hurt a thing.Make sure that you are not adding draw weight to a point that will make shooting uncomfortable.Being able to maintain proper form and execute perfect shots is WAY MORE IMPORTANT than a few feet per second.
An arrow that may actually shoot flatter for you but may be the same weight and speed at the bow is the Easton ACE's.They will give ME a gain of 3 yards at 50 yards and I would only gain about 11 fps with them.Usually 11 fps will only give you about 1 yard at 50 but ACE's just cast flatter.But be prepaired to pay big bucks.[

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I think you need to just take the hush kit off and make sure the cams are set up properly and quit looking at the chrony and just shoot.I have shot my best 3-d scores at 263 fps and 270 so just learn the yardage and make the shots.

If it still bothers you that much then a harsher cam will be in order and that is just about the best way to add speed and keep the shootability of a moderate riser designed bow.
1 more thing,I would not go any lighter on the front of the arrows than you are now.Your foc will get too light in my opinion to be shootable in all conditions.