Heres the deal guys. I recently replaced the rear stock speakers in my car. The new ones that i replaced them with required more power so i hooked up a 300 watt amp in my trunk to run them. Now when the car is running an the radio is on there is engine noise coming thru the rear speakers (sounds like a high pitched noise that increases when i press the gas pedal). I talked to my friends and they asked if i had ran the RCA cables and the amp power wire on opposite sides of the car and i replied no. They said that having the wire together was most likely the problem. I rewired my car this weekend and the noise is still there. Also have tried different ground places in my trunk and some places result in overwhelming engine noise. Any ideas as how to get rid of the noise

Get a grounding kit.
I have the same problem in my audi with my headunit and speakers. I kind of like it though becuase it gets louded with the rpms and it tricks people into thinking its a turbo spooling up

you don't need a grounding kit . you just need to hook the ground wire from the amp to a better section of the car . try at a strut bolt or bumper bolt . just make sure you grind off the paint where its going to bolt to on the car .

If you want to get rid off all the hiss a grounding kit isn't a bad idea though, btw since your on x-s, im sure you could make your own anyways

First do what C89ZX7R says. Engine noise is basically just a bad ground. Try sanding down that area where you are grounding to. Or find another spot for the ground.