I am needing to drop the exhaust on my '89 IROC (at least, I need to drop enough to get the muffler to drop). My Haynes manual says to "unbolt the exhaust at the catalytic converter"; however, my CAT is welded in. My bet is that it's not the original CAT (at ~117K miles, I sure hope it isn't), but I'm not completely sure. Did these cars come from the factory with bolt-on catalytic converters?

Do new catalytic converters generally come with bolt flanges, or would the flanges need to be fabricated and installed?

Lastly, what pipe size do I need to be looking for to replace my existing CAT?

Thanks

 

Sancho,

My '86 has the cat sleeved and clamped in, just like a muffler. It's the original. A lot of my other cars have flanged cats - bolted in.