How to add as much as possible horsepower i can to my 1997 bmw 540i ?

Its a 97 540i 6 speed . The things I already have done are:

K%26amp;n intake . Performance muffler. Removed resinator.



I already Know about the Dinan , so if you know anything else that can help me to improve HP ( cheap) let me know. Thank you .How to add as much as possible horsepower i can to my 1997 bmw 540i ?You can do install a good turbo or supercharger.



OR



You can lose some of those weight on the car to get a better power to weight ratio.How to add as much as possible horsepower i can to my 1997 bmw 540i ?Nothing really. You could probably swap in a modern m3 engine (v8)...but it would cost more than your car is worth.