I posted this under V8 engines but didn't get much of a response. Thought maybe posting under the 2004-2008 f150 might help get more responses.

I have a 06 f150 5.4 I used this forum before with fuel injector issues and you guys fixed me right up so here I am again looking for help.

I was driving home this past saturday and this awful squealing sound started coming out of the passenger side. I took it to a mechanic he charged $40 and told me the valves needed to be replace so i am going for a second opinion. I would like to think this will be an easier fix like the belt tensionor pulley or the water pump. This sound can't be heard at idle speed but sometimes just above idle like 1000-1200 rpm but not when revving the motor, but it can be heard at all times when going down the road and giving it gas or like when putting the engine under strain. Now to throw another wrench in there, I have true dual flows "two in, two out" and prior to all this crap happening, it used to rumble and purr like a kitten. Now, it sounds almost like stock exhaust. Any thoughts and advice would be greatly appreciated

Also one more thing...Any thoughts on cutting the catalytic converters off?? If I do it aside from the environmental affects and the laws, would I have any side effects on the engine as far as throwing codes, not running right, and issues with the O2 sensors????