Greetings: I've seen quite a few threads about people using test pipes and gutting the precats. Aside from expense, why not just gut the cats, as well as the precats, and not buy test pipes at all? I don't want to get into a big moral debate here on the right or wrong of test pipes, and the impact, if any, on the planet, etc, etc. I'm just interested from a technical point of view. Is this feasible, or are there problems with such a setup?