The passage in question is an excerpt from a novel.
Background info: B is an inventor who works for the government in the story's universe and has created his own mechanism in secret that is capable of gathering various information on the public (their identity, whereabouts, activity etc.) that surpasses the mechanisms the government already uses. A is his assistant.
A: it's only natural a mechanism invented by you would surpass the others currently in use. Though, I wonder what could have possibly occurred that caused you to invent your own mechanism?
B (ケン): Putting your trust in things so easily is a foolish act that lowers our performance. そこは『足りぬ脳味噌で熟考を重ねて検証もしたが、やはりケンの造り上げた機構の方が全てにおいて上だ』と言い給え。
I'm having troubles parsing the part I left untranslated in B's dialogue.
I tried breaking it down like so:
そこは~と言い給え - to say here that ~
足りぬ脳味噌で - [with/through/by using] inadequate brainpower.
熟考を重ねて検証もしたが - carefully considering re-examination too, but~
やはりケンの造り上げた機構の方が全てにおいて上だ - as expected, a mechanism created by Ken is better in everything.
It's hard to see how this all fits together.
I would be so grateful if someone could correct me where I've gone wrong!