Join Date: Nov 2003
Location: Houston Texas USA
Well exhaust fumes in the cabin and exhaust emissions are separate issues. If you have leaks in your floorboard, improper routing of the exhaust tips, all these will cause exhaust fumes in the cabin no matter how clean the exhaust is.
I've never seen an OEM catalyst without an O2 sensor, and I doubt a Catalyst will last very long without the O2 sensor feedback loop. I went to both of those sites, and they both sell the same product. One of the sites has the following wiggle phrase at the bottom of the page
"...It is important that the vehicle’s engine is tuned correctly. If not, this can cause the converter to perform at a sub optimum level and possibly cause damage to the converter...."
Reading between the lines of your post. Are your Solex carbs not adjusted properly? Or are the carbs so old that they can't be adjusted properly, meaning that the throttle shaft bores are wallowed out, and expensive rebushing is required?
Wise use of your money would include fitting an O2 sensor bung to your exhaust pipe and hooking up a wide band O2 sensor. This will guide you in adjusting and diagnosing your carbs. if you find that your Solex carb are indeed worn out and too pricey to fix you can still buy rebuilt Weber cars at reasonable prices.
Hope this was helpful