i am considering using a walker CAT, with my existing piping going back to muffler on my stow and go 2006. thanks for anything you can remember or help me with. I would appreciate help in this area. Sounds like a big project.
but i imagine installation if went somewhere would cost about 200 bucks. Help me.

Let me ask you to confirm what I would like to do if this is what you may agree with as procedure.
1. use all the existing original piping going from CAT into the muffler pipe where there is a clamp that joins them together close to rear tire?
2. then cut through the pipe .5 inch at the location where the old cat was welded to the piping?
3. then widened the cut from .5 to 1.5 inches
4. then pull the existing piping going back to muffler forward (I hope there is some sort of slack to do this or have enough pipe protruding from the walker cat to reach to the existing piping) then slide the walker neck coming out of CAT t inside the existing pipe on the van and clamped it up?

A) How far downstream on the pipe referenced to the weld location of the should I cut the pipe?
B) Can I use my existing bolts and flag cut on the fan after wire brushing them? it cost $40 bucks at dodge for them m8x1.25x45? ( went to home depot and found 40mm length bolts. how critical is it to use 45mm? have you been able to use 40mm?
I know flag nuts are preferable for ease but 4.50 vs 40 cents a piece is hard to justify.

I did think about buying the complete cat from eastern that has all the piping for 180; includes clamp and gasket for manifold cat interface. I just though the above procedure would be easier and advance auto even though more money allows me to bring
back for 50,000 miles warranty. where online i have to send back at my expense and a really big deal about returns. but easter would be 40 bucks cheaper then walker at advance.

any tips or advice