The Lexus AFM *housing* is a popular swap for the stock KVAFM's housing. It'll let 25% more air in, but requires you to upgrade your injectors as well, 550cc injectors are what you'll need.
Might as well check the timing since the previous owner mentioned it as well. Don't forget to set the TCCS to the diagnostic mode before setting the timing... and check for error codes while you're in there.
As for the gauge, some MKIII's came with 150MPH gauges and others with 160MPH gauges. You need to swap the whole gauge, not just the face... and the gauge includes the odometer, I hope you didn't buy the car based on the low miles.
