The hoses that connect to the tank and pump will blow. It is said that it ruins your RF20.
Where, exactly, have you heard this? You've answered several mod questions in a way that makes me suspect that you've never modded and don't really understand the historical context of these questions.
I just think you should limit your responses to personal experience or hard facts rather than speculating just so you have something to say.
deth,
Your homedespot link gets me a bunch of generators so I can't address the specific tubing you're looking at. The problem I see with your idea is this: increasing the pressure in the RF20/WF/PC does not significantly increase the range. I've seen people comment otherwise several times, but my personal experience is that you'll get an additional 5' at best and you can achieve that with heavy rubber bands so this would be overkill. Beyond that, additional pressure merely increases your rate of fire - something most people find undesirable in an actual nerf war context.
The only known way to significantly increase the range of an RF20 is to both band the bladder and impede the travel of the piston so that more (higher pressure) air is required to reach full extension and air release. There have been a number of threads on this, the first one I came up with was
this one from a couple years ago.