yes the 2.5 is way to hot at 5v, those are meant for 3.3 volts or lower, with ptb they can work at 3.7 just fine.
you need the 2.8 but more preferably would be the 2.9,3.0,3.2 ohm'd Xl c-e2.
those are perfect at 5v and the 3.2 is good at 6volts too. I use the 2.9 and 3.0 ohm at 5volts in my videos in my link below.
I dont think anyone has the higher ohm's ones in stock but if they have the 808 xl , those where usually all at 2.8 to 3.0 ohms
if you would like one or two to test and cant find any vendor with any in stock. pm me your addrs and ill send you a 3.0 ohm's 808 xl e2 to try.