Damn good question......lol!!!......from experience!...the AR-X was like a bus on cross-pliers standard.....that being said it was still far better than a Liberty, or an Holden Adventurer.....it's just got a weight issue(It's a fat cow in other words...1,780kg's dry weight)
The RS or RX are pretty good straight out of the box(alot lighter too)....with a good set of pads and tyres(not semi slicks either) I reckon I could crack 2 minutes at EC.....no way with an UNMODIFIED AR-X though!!!...but if it rained the AR-X would be quicker.