IIRC (its a while since I used my 106), there an "all speed" hacked firmware on www.rpc1.org that allows any media to be burned at any speed (I think by the dangerous brothers). Used to use it myself and it worked well.
Unfortunately rpc1.org is down at the moment as they are moving the servers.
Be aware however a lot of 2x media (where the hell you even get 2x media these days?) will not burn well at 4x, so you may well be stuck with the decision to either burn at 2x, dump the media and get some 4x, or dump the drive and get something speedier.