Last week I noticed a metallic rattling coming from under my car during accelerations at about 80% engine load. I had to take it in for an oil change anyway, so I asked the dealer to take a look. Turns out the heat shield over the catalytic converter had rusted through 3 of the 4 bolts. They pulled it off an we ordered a new one. When they tried to put it on, they claimed they couldn't get the bolts off because of the rust and corrosion. They told me I could pay $1700 dollars for a whole new converter or I could just go without it. The service guy told me he didn't think it would be a problem to just leave it off. I'll hit the quarter million mile mark in the next few months, and I'm hoping she'll go another quarter million. So, do I really need the shield? Any other options?