Actually, this isn't quite right. In order to use Boyle's law, the pressures have to be absolute. both the 90 psi and the 2 psi are relative to the atmospheric pressure (gage pressure, psig). the absolute pressures will be 90+15=105 and 2+15=17 psi (psia), respectively. this works out to about 4.2 cubic feet of air- probably no where near enough to blow your hulls apart.
Having said that, I still wouldn't try this on a hull I ever wanted to use again...
you would be amazed at how much volume of air is in that 5 gallon tank.
boyles law applys if there is no temp change( there would be, lets assume not to keep this example easy)
if you have 90 psi in a 5 gallon tank, there is ~ 231 cubic inchs per gallon.
so the eq would look like this:
90 psi * 1155 cubic inchs= 2psi*v2
so v2= 51975 cubic inchs or ~ 30 cubic feet of air. I don't know what the volume of H17 hull is, but I'd guess that 30 cubic feet is enough to fill the hull up atleast twice.