Depending on your case/PSU layout, mounting the power supply "upside down" can actually be a very efficient method of managing heat issues.
I have set up several systems this way.
All of my PSUs have been ATX compliant which means (among other things) that the intake fan of the power supply is also supposed to help evacuate the waste air from the CPU socket area...good for the CPU/HSF maybe, but a terrible burden for the PSU (Note:this scenario holds true for most cases, but not all. In my Silverstone TJ06 the PSU is drawing it's intake from the HDD cage...either way, the power supply's intake air has been preheated- which is the scenario we are trying to avoid.)
Start by reversing the intake fan on the power supply ( kiss your warrantee goodbye at this stage), so that it exhausts air from the unit ( it should be sucking from the back now...if there is a fan in the back reverse it also).
Flip the PSU over and mount it.
Depending on your case, if possible, cut a blowhole above the PSU's exhaust (formerly intake) fan.
Now the power supply is drawing fresh air from the backplane of the case and exhausting right out the case roof.
On an Antec PSU with sensor operated fans, this change will significantly reduce the operating RPMs of the exhaust fan as the unit is no longer working with the pre-heated intake air from the CPU.
You may have to bolster the cooling/removal of air to the CPU/HSF as the power supply is no longer performing this function.
This is a lot of work if your only concern was the aesthetics of the stickers ( which aren't that hard to remove anyway), but as part of an overall heat management solution it's well worth the effort.