I'm curious what your trying to achieve? 3800's are low RPM torque engines. The only effective way to add power without a Power Adder (Nitrous, Supercharger, Turbocharger) is to spin the engine at a much higher RPM & raise the Compression Ratio which would require a bunch of supporting modifications......And still get your doors blown off by a well tuned Forced Induction car with a bone stock long block!
You could find a wrecked Lacrosse Super & swap in the LS4 5.3L....Delete the AFM, Add a mild performance camshaft & make 320hp/320tq real easy!!