Mitsumi 485GTE 54X32X54X only burns at 16X

I got this drive about a month ago with rebate and everything. I only had a chance to play with it for the last couple of days. The biggest problem i have with this burner is that it cannot burn at anything higher than 16X with any cd that i have. When i bought the drive, i got some mitsumi 48X cd which i would assume that i should be able to get at lesat 32X out of it. I installed roxio5, 6 and nero 5 and 6. All of them gave me the option of 54X max when i don't put cd in, but once i put my SOURCE cd, it limits my speed to 4X or 16X. Now...i wouldn't be concerned with this if it was the blank cd that i put, but how can it determine my burning speed with a source cd? I have XP at the moment with SP1 and all updates, plus ASPI from Adaptec. I have tried mitsumi cd, some cd with label(48X) which i can burn at 40X on LG, sony 48X. None of these work at anything higher than 16X. I have the latest firmwire from mitsumi and all the updates for the software. I do not know why this is still the case. I emailed mitsumi, all the said was, try these cd which will work at 54X. That's not the point here....i'm not trying to burn at spd like 54X, but i'm more looking forward to things like 32-48X! I am thinking of returning this burner to the place i bought it (Futureshop in Canada), but i already cut the UPC code for rebate. If nothing works, i'll request to return it back to Mitsumi. This is just unacceptable...Does anyone have any suggestion or experience with this drive?