My son's 351W had developed a massive header leak (so what's new?) and he had tried in vain to get the bolts started on the header after replacing the gasket. I finally decided to get involved a few weeks later and I walked out to the garage on a beautiful Saturday morning and, while cursing a blue streak, managed to get all the header bolts started. I snugged the header down and my kid fired up the engine. Same stupid leak! I finally caved in and took it to a local muffler shop. I figured maybe the header had a hole in it or the flange was distorted. I get a call from the muffler shop to come have a look at the problem (I know the guy). There on the second and third exhaust ports on the driver's side were huge chunks of the previous gasket still stuck to the block. Hmmm....I wonder why it wouldn't seal. My face must have turned several shades of red. Scott the muffler guy had a good laugh and he charged me $150 for all the gut busting he went through to get the stupid header on the car. Doh!