meow (cat question)

my barrage of questions:
i'm thinking of gettin guy at an exhaust shop to do the exhaust for my 99 SE (3.8L) and i have a muffler picked out cuz i'm keepin it single...
should i bother gettin a high-flow cat? i'm thinkin it'll be cheaper to get the install of the pipe, muffler, ubend delete, (res delete), and cat all done at once.
Also, will a universal magnaflow high flow cat work? or is it specific in any way?
And what about these air tubes? help! :confused: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33629&item=7987863476
What Size to get?
They're cheaper on ebay... TIA!
My DP is stock and my only mods are 180 stat, DHP, and a FWI

Matt

You dont need the ones w/ air tubes and I think the stock piping is 2.25.

I just had my cat installed and had them cut the y off and am now just running a single muffler. I also bought it off ebay, not the magnaflow though.

If your deleting the ubend and resonator you'll save some money becuase all they'll do is run a single pipe from the cat to the muffler