I have one for the reason Mark mentioned its required on the track. Mine has ports on the top and bottom so I put a tee fitting on the bottom and put a clear hose connecting top and bottom then ran the overflow line to the canister. That way I can see the level of coolant in the overflow.
-1994 Trans Am Gt: caged, CC503, Garrett GT45, 6Lbs, 3.73
-2011 Camaro SS convertible: SOLD