I know I need to replace my catalytic converter... probably due to slow coolant leak through my head gasket that I found after buying my truck 7 years ago. Because of my high mileage, mechanics are quoting prices that are higher than what I paid for the truck. What are your thoughts on sealant products like this: K&W Permanent Metallic Block Seal I'm just looking for something that will allow me to continue driving my truck. I don't need for it to look beautiful. If none of these products are recommended, I may just install the new cat and O2 sensors for my California smog check and then remove them and replace them with the old parts, till I repeat the process 2 years on with the next required smog check. Please share your thoughts on this.