Just finished this on my car and I kept close track of what I did and spent to make it happen.
Question: What are they?
Instead of using rubber for your coolant lines, you use 3/8" aluminum line and -6AN fittings. This is the same stuff FM sells for nearly $200; make it yourself for half that.
Question: Why are they better:
Answer: They will last, literally, forever. Rubber wears out and becomes hard. Even SS line has a life expectancy; it's still rubber or teflon on the inside. Hard lines have no rubber, so they last a LOT longer. You don't have to replace them, since they essentially don't wear.
You need to have a fabrication shop or a friend with a TIG welder put a -6AN bung in place of the steel fitting pressed into the stock water neck. You can have another -6AN bung welded to the front water neck, or you can use the M12 port on the side of your block (pre-96 guys).
I ordered a few items from AN Plumbing that could be gotten cheaper on Summit, but Summit was out of stock. AN was also cheaper than Summit on some items. Cross-check yourself before ordering to get the best price.
(1) or (2) -6AN male weld bungs (Summit Racing PRM-15669, $4.25 each)
(1) M12x1.25 to -6AN male adapter (AN Plumbing 991945, $6.79 each)
(2) -6AN tube nuts - pair (Summit Racing SUM-220633-2B, $1.25 each)
(2) -6AN tube sleeves - pair (Summit Racing SUM-220634-2B, $1.25 each)
(2) M14x1.5 to -6AN male adapter (Summit Racing RUS-670520, $4.95 each)
(4) -6AN male to -6AN female 90 ell (AN Plumbing 966306, $4.95 each) [Note: You might be able to get away with only a couple of these, one at the motor and one at the inner turbo. I bought 4 just to make the bends a little cleaner]
(1) 25ft spool of 3/8" hardline (Summit Racing SUM-G2538, $16.95) [you can get a 10ft spool for like $10, I decided to buy extra and maybe produce a kit?]
(1) Summit Racing 37deg flare tool (Summit Racing SUM-900311, $26.95) [Note: You may not need this, but nobody I knew owned a 37 degree flaring tool. 45 degree WILL NOT WORK.]
Fittings cost is $64.33, total including tool and $20 in welding for me was $111.28 plus shipping plus tax on the AN Plumbing items.