I'm pretty sure I have a bad exhaust manifold gasket(s) on my '05 Sierra 5.3L. It's recently started making a ticking sound at the same speed as the engine revs, but only when cold and under load (in-gear and accelerating). Once it's warmed up the ticking goes away, and there's no loss of power. I've done plenty of searching and am pretty sure it's the gasket based on all the symptoms, if anyone wants to chime in another possibility that'd be appreciated. *EDIT* I am also getting a trouble code- P0131 "02 Circuit Low Voltage" Looks like that could possibly be related to an exhaust leak? Assuming it's a bad gasket, I don't think it's something I want to do myself. I'm not extremely skilled mechanically- I change my own oil, installed a K&N intake, changed my brakes, but usually don't take on anything more complex than that, especially when there's a chance a mistake could cripple my only vehicle... like breaking a bolt. I'm also not very good at the more meticulous side of things- I'm worried I wouldn't get the gasket on straight and it would still leak. I can't even put a decal on something straight. Unless someone wants to convince me it's easy and painless, I'll probably take it to a shop. That being said, I'm guessing I can expect to spend anywhere from $300-$500 at a shop? I see the gasket itself isn't too bad, and maybe a couple hours of labor, but the shop usually adds some 'insurance' for themselves if they break a bolt? And most importantly- I have a busy week and a 500 mile round trip coming up next weekend for Christmas. Is it really important I get this taken care of before then, will I do any serious damage if I drive it like this? The noise goes away once it gets warmed up, but I realize that doesn't necessarily mean it's not still a problem... Thanks in advance everybody!