Summit makes a rebuil kit for the 84-91 buick 231 V6 Turbo, with Forged pistons its gonna cost $449.95, with Hypereutectic pistons its gonna cost $319.95, not bad for both prices and kit includes: pistons, piston rings, main, cam and rod bearings, high volume oil pump, gaskets, freeze plugs, plastigage and and assembly lube. The compression ratios are calculated with .30 over pistons