you can use the pinch test for the low end or you can bring the car to a stop,dont touch the throttle, just let it sit for 10 seconds. the idle should drop a couple of rpms after about 5/6 seconds this is due to it starting to load up. then pull full throttle you should see some smoke and the car will move out without too much of a bog due to it loading up. when you are running keep an eye on the exhaust, you should see some smoke