hacked so you can get faster download speeds, is it safe?????
This isn't necessarily illegal, so I don't see the problem in talking about it.
That said, your line speed (at least here in the UK) isn't dictated by your modem / router, it's dictated at the exchange, perhaps even before. You most definitely aren't supplied with a super fast connection that's deliberately made slower by the modem your ISP gives you.
Some routers can have their firmware flashed to custom / hacked versions which may allow the on board modem to work more efficiently, but you're not going to see super fast increases this way, if any.