The most easy tuning that can be done to this engine is removing the “half moon” from the butterfly of the throttle body. This has as a result that the engine will get more air into the engine at a less opened throttle and therefor the engine will pick up sooner at low engine rpm. Better throttle responce.
The upper picture shows the intake manifold with the throttle body.
Undo the 4 nuts that attach the throttle body to the manifold and remove the throttle body.
Take off the “half moon” from the butterfly by undoing the 2 screws. These are the 2 upper screws. In the picture you can see that 1 of the srews is already removed.
Since we now have 2 open holes in the butterfly these 2 need to be closed. The easiest solution is to put in 2 M4 bolts and self locking nuts together with some Loctite. Caution, these bolts and nuts must be 100% secured otherwise a terminal engine damage can occur. In the upper picture the bolts and nuts a in place.
As you will see now the butterfly is flat. Clean the throttle body with some brake cleaner to be sure no residue is left in.
Good luck.