[shawn908]

Thanks all - the responses here resonate for me on this problem...
The views into the pipe also clearly show a difference in the functional diameter of the "cat" on my car vs an engineered alternative - suppose if a large diameter empty tube with irregular interior surfaces was an optimal choice for exhaust gas bypass pipes/test pipes would look different.
The Sawzall is just too big to get at more than one bolt head - not feasible as a tool here. I looked into a cut off wheel but after 5 or 6 YouTube videos - agree with Pigeye - I think these may end up being be too large for the tight spaces. If a Dremel has worked - I will stop by the local hardware store (shop local) wearing a mask and see what they have in stock. And buy several cutoff wheels.

tirwin - I do use a ZDDP - Joe Gibbs - so good to know about effect on a cat. More reason to go bypass pipe. Thanks also for the offer on the test pipe - for once.... I am going to buy new and get both from M&K.

I like the description of the bypass on M&K site re: potential performance increase - but if the bypass pipe and the single in/out is louder and lighter its a win for me. Another weekend under the 911 approaches.