Errrr, no
I was just going off advice from Abbey when I was looking at a TT conversion.
A true dual helps but you dont HAVE to change to a TD as you implied
Also if your going TT headers are a waste of time as the TT kit will come with its own manifolds. I did headers, paid 3 times more in labour than I paid for the things but I gained 13hp on an untuned engine