I recently put low ratio diff gears in my GQ and it has completely changed the feel of it. I'd highly recommend the diff gears with 35's as it brought my ratios just below factory gearing. I now have to do 110km/h on the speedo to actually do 100km/h and still only rev at 2200rpm in 5th. I'm not 100% sure the gear ratios are the same on the diesel and petrol GQ's.