I need some help guys. I'm new to Mustangs and I'm learning as I go. Here's the deal; my car has a rough idle. On the scale of 1 to 10 I'll give it a 4, so its not to bad. If I listen to the exhaust note at the rear of the car the passenger side sounds choppy, but the driver's side is all fivers. And also, above 2000rpm there's a pinging, don't know if its from bad gas or timing or both. I really started to notice this ping yesterday when I changed out the factory H-pipe. Please help me!!!!