I have an '07 GTCS purchased in 2008 (120K miles on it now). The 4.6L 3V has been very reliable for me in stock form. The only challenge has been changing the spark plugs. The 3V heads have a unique plug design that can become a nightmare of you can't get the broken ones out with the extraction tool. I only broke off 1 ;-) But had the tool in hand. And successfully removed the broken end.