what kind of rca's do you have? make sure they're decent and have a nice shielding on them. i use the monster xln rca's and have put the rockfords dual twist rca's. also if it's running along any harness they give off some noise.

how high do you have your gains on your amp b/c if you have noise and your gains are pretty high that will magnify your noise.

i would do what rcurley55 says b/c i'm not to familar with fusion but from what ones i worked on they're not to good with noise. i think they're s/n is kinda low so it won't be able to filter out the noise.