cheap ways to increase torque and reduce fuel for CLK320 Cab (W208)

what are the cheapest and most valued-for-money to reduce fuel consumption and increase the torque (acceleration)
of a CLK320 Cab (W208)?

someone suggested me
(1) use better pulley and headers
(2) change the exhaust

how about changing the chip? e.g. www.powerchipgroup.com?

does it work?

thanks for any suggestions!