Hello All, I'm getting a PO430 Code (Catalyst Efficiency Below Threshhold) on my '97 K1500 Silverado. Its a single cab, short bed with a 5.7. I checked the torque on all of the exhaust manifold bolts and seems to be good but on cold mornings, it sounds like a diesel truck. Could this be the reason I am getting the code? The truck has about 174K miles and still running strong. I bought the truck with 90K miles haven't replaced the converters, so it may be time. Suggestions? Also, I priced the converters at the dealer (just in case)...$1300!! I think I might be able to get OEM stuff a little cheaper but its still a ton. I saw some Walkers on Rockauto http://www.rockauto.com/en/moreinfo.php?pk=3381939&cc=1051175&jsn=607 I know there are some non-OEM parts that you can install and get away with but I was told the Cats aren't one of them. What do guys think?