^^ Not quite true. ^^ The key switch is still fed direct, what the relay is mainly for is to relieve load on the "run" circuit, and part of that problem is that if you don't, the voltage regulator is "low," and this causes overcharging. But during start, the IGN1 and ACC lines are dead, so the only thing the key is supplying is the small amperage of the ignition line in the engine bay, and the starter relay. If you still suffer much drop "to the ignition" during cranking, you will just about have to either install a second relay, or fix the entire drop problem
Id try it first by simply monitoring a voltmeter, connected to battery PLUS and the brown wire. This will tell you the total drop from battery to the brown circuit. If that is excessive, and if you are getting below 10.5V to the igntiion, there is a couple routes you can go
1.....If the drop is only through the bulkhead terminals, you can fix or bypass them
2......If the drop is partly / substantially through the ignition switch itself, you'll have to find a good igntion switch
3.......yet another work-around is to change the starter relay to the later "Jeep" style which has an additional contact. This contact can be wired to replace the brown bypass circuit
Notice the added terminal at far top left. The downside of this relay is that the nice big stud has been replaced by a different terminal.
View attachment 1715866252
4....Or you could add a second Bosch style relay wired to fire with the starter relay, and use that relay to operate the brown bypass circuit
AGAIN I WANT TO emphasize, I would first check this and be certain that is needed.