should i swap motor,need more horsepower

We run a very cheap built 400 in my sons Dart. He is on a tight budget like me so we used alot of parts we had. It's a stock stroke .030 over 400 with KB pistons with stock 383 crank and rods. MP .557 cam and bone stock Eddy heads. Performer RPM intake and 750 DP. Dynamic 9.5 convertor and 4.30's. Runs 11.50's @ 116 in a real drive anywhere all stock body street car. Ron