I have seen some camaro guys swap from 2 piston to the older 4 pot CTS-v calipers, and there was an article on one site where they swapped the 2 piston camaro calipers to the newer 6 pot CTS-v calipers and seemed "pretty much" bolt on.
I bought caliper brackets from Purple Reign that uses the 2 piston camaro ls calipers and have thought about trying the 6 pot but the calipers are expensive and 14" rotors are another cost when the 13" or way more than needed. I might go to the 4 pot calipers if find a decent deal on ebay..
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87GTseries 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a---sold
Northstar Rebuild