I recently installed a used ATS turbo kit I bought off eBay. If you know your way around vehicles and machinery it's not difficult. The challenge is in figuring out how all of pieces fit together. Also, you may think your kit is complete, but they rarely are, so fabricating skills and general knowledge of hardware are a must.
A parts diagram is helpful if you can find one. Installation instructions are a real plus. I wasn't able to locate this for my ATS non-wastegated kit, but I did find some for their wastegated version, and while not identical, the kits had enough in common that I found the instructions extremely useful. I did some searching and found a link to the Banks Sidewinder (wastegated)
owner's manual and installation instructions. Hopefully they will be of some use to you.
Have you called Banks? They may very well have odd pieces you might need like brackets, heat shields, rubber gaskets and seals, a transmission dipstick, and possibly a paper copy of the manual for your kit.
McMaster-Carr sells o-rings by type and size if you can't find them elsewhere, but you have to buy in small quantities, not singles. Be sure to get Viton for anything in contact with fuel or oil.
When all else fails, try a good hardware store, or even HD/Lowes. For example, my seller failed to include the rubber grommet that fits into the valley pan, and ATS no longer sells them for my kit. I found a rubber gasket in the plumbing departrment at Lowes which needed a little trimming with a razor knife to fit the bill.
Good luck with your install. Sorry I don't have specifics for the Banks kit, but there are lots of knowledgeable folks on this forum, surely someone will have detailed info.
