Yes, the supercharger requires high octane fuel.
Look for coolant leaks (particularly from the front of the engine which may be coming from the head gaskets), cracks in the exhaust manifolds, and especially look for an oil leak around the rear main seal. My RMS leaks a little, but not enough to justify the $1000 repair bill.
If the carfax comes back saying no accidents, don't necessarily trust it, I have been in two accidents and neither was reported on a carfax report. Look for any signs that it could have been in an accident, check for uneven tire wear.
I have the SC version and I love it. I have clocked almost 50,000 miles and it has been a great vehicle. Except for the gas mileage.
