My mechanic said I need to replace the manifolds, risers, and spark plugs on my 5.7 Gi-E engine. He said there is heavy rust do the risers "misting". The quote is around $1500. Does this seem like a fair price? Is this something I can do on my own? I have automotive mechanical experience. What about parts? I have looked around and found some places that sell each piece individually, but I wouldn't be sure what all to get. Does anyone sell an all-in-one kit? Any advice or input is greatly appreciated!!