Just seeing if any one else has picked up one of the newer 5500 psi carbon fiber scotts. I bought a 5.5 Scott I think 90 min last year on eBay for a reasonable price and still lots of good years for legal hydrogen testing if needed. Just letting you know they are for sale used on eBay from time to time. The 5500 psi tanks make shooting 4500 psi big bores regulated possible. I have yet not invested in a long-term reliable air source. I currently use a yong heng but am going to invest in a larger air driven booster pump to fill.my 5500 psi Scott scba. I'm just putting this out here because the components are available to fill 5500 psi tanks and regulate with aqua environment regulator to 4500 psi . The 4500 psi kits in Airforce Texans do make a amazing amount of power with the heavy slugs per caliber. I shoot tethered 90% of the time.