I have all the general mods (AR removal, boltsled reinforcement, custom o-ring with silicon grease, beefier catch spring etc). Although, the only reason the average is so high, is the unpredictable fish-tailing of the streamlines.
I haven't measured flat, but I'd imagine it would be drastically lower ranges. If I removed the ranges of the freak shots, I'd say it would be closer to 100 feet.
I'm waiting on some stefan's to compare data, and will no doubt upgrade to Littlebro's aluminium lamination reinforcement on the boltsled.
And before I get flamed for being a noob, I may be new to Nerf, but I'm certainly not new to using a tape measure....