what hp gains can i expect from this swap? i read somewhere that the y8 is the "type r " of the d series manifolds

 

yah its often called that but, the differences between the z6 and the y8 are basically that the y8 has a curved intake port vs the z6 has a flat one...

basically the y8 is good for producing good low-mid range power and the z6 is specially for top end power...

this topic has been covered several times, its pure preference in the end... do some research im sure ull find something

 

If you already have a z6, I don't think that the gains are worth the effort. Save your money. Edelbrock will soon be releasing an IM for the 92-95 crowd.