Highflow cat when buying Greddy?
 

When installing the kit, i believe the stock O2 sensor will be stripped and i will have to place a new one in. Also the O2 sensor that's going to go to the wideband afr gauge as well. If I want to install the highflow cat later,
how hard will it be to take those O2 sensors out of the stock cat and put it in the highflow cat?
Cuz what I want to do is install the kit without the highflow cat to prevent the need for tuning and run it a while. Then looking at how the kit performs, buy the highflow cat and get the emanage tuned by an expert. Does this sound like a good idea?

I didn't have anyproblems using the O2 sesor in my original cat in my hi-flow cat unit. But I am now, even after putting in the updated Greddy map, having a bad backfire problem. I think I will be putting my stock cat back in soon. Rudy8 said it helped him greatly. I may to try to tune it our, but I might just try the stock cat back in for now.