It maybe to do with the electric throttle rubbish we have nowadays.

I can't see how any auto can better a good driver that knows what he is doing shifting gears manually at the right time in the meat of the rev range.
I know some people have no idea when to change gear, so as to make them perform at there best.
I had a mate that his old man bought him a new car every year and he would come over to let me drive them, he loved that because he said, f you can make the car go so much better than he could himself, he would just rev it out too far and just could not understand or have the feel when to do what when.
Bloody funny bloke he had a photo album full of all the cars he smashed, all down to the door handles he said and one they had to cut him out through the floor of the car, one he showed me that he left a photo of it all smashed up in the owner manual book when he sold it, I remember him smiling ear to ear showing me the crazy little wog bastard.

Hey my mate picked up his SSV ute 375KW it says and manual box is fine.
It does not say walkingshaw kit but has 4 into 1 extractors and full exhaust job and other bits and re tuned.
She has some grunt.