b16a exh. manifold

i’m planning to swap a b16a soon, i’ve been doing alot of searching and researching. In one of the teg tips swap guides, the writer says he had to make a custom pipe for the exhaust manifold to the cat. Is this true in all cases?

also…i don’t plan on using the b16a tranny. Mostly because the gearing is way too short for long highway driving. So i’m wondering how would the car run with the LS tranny?

any input would be helpful thanks