I have the 800mm BF109 and Spitfire. On those I put 1/2 oz lead weight (that's 2 1/4 oz squares) under the cowl using Tape.
I understand that the other 800mm arfs are the same.
3/4 oz was too much and 1/4oz was not enough. 1/2oz was the sweet spot.
I'm using everything else stock.
Wire on aileron horns are all the way out
Wire on elevator horn and rudder are one hole from outter most hole.
I'm using stock Tx on them.