I've had my car in the shop for over 6 months performing a 3.0L hybrid conversion. I employeed a one man shop that I later found to be a BIG mistake. He took 5 months with the car and for the last month and a half fought with a "valve-train" noise. he replaced the lash adjusters, timing chain tensioners and even checked the crankshaft postion wheel. Still the sound remained. I eventually pulled the car from him and gave it to the local SVT dealer. To make a long story short, the engine eventually came out of the car, the heads were removed and we noticed the original shop reused one of the 2.5L head gaskets. Therefore everytime a piston extended, on the one side of the engine, it would make contact with the gasket. In retrospect it sound like a a playing card in the spoke of a bicycle.
I am posting this for two reasons 1) as a warning to others to seek a qualitified shop and 2) In case somebody else has this problem they might find this post and save them alot of time/money.
P.S. Now that this has passed, I look forward to all of the modifications that I have made. See you are IRP next year...
this couldnt have been a mistake! it was intentional. 
theres no way you can over look putting a smaller gasket on a bigger bore engine! 
What a idiot! Get all your money back and then enough to cover the SVT repair! Don't stand for it!