STEREO INTERFERENCE HELP!

I seem to be having some interference through my stereo when the engine is running, when just on ignition the stereo works perfect. I understand that this usually means installing a suppressor between the coil positive and ground. However i have done this and still no good. Has anyone else experienced this problem and if so could they throw some advice?

The car is running perfect now and it would be cool to get some beats with it all!

suppressor between alternator output and ground. If that fails then could be your leads particularly if copper cored. make sure your earths are good too.

mk1golfdriver said

suppressor between alternator output and ground. If that fails then could be your leads particularly if copper cored. make sure your earths are good too.

So add this as well as the coil suppressor?