Deffinatly go straight exhaust I am running 21/2 on my 78Z and it made a big difference in my performance. I also got away with not having to run a cat. in my state they do not smog. In the book for exhaust the early 78Z,s did not have cats except in cali. So I lucked out. Now if I could just get some headers.
Something else I did was puled the fuel pressure regulator off a 79ZX and it made a nice little diffrence.