when buying parts for a d-series engine, do i need to stay with the parts that are meant for my engine (sohc d15b) or can i buy parts that fit other d-series (d16 the 88-91 si motor)? my reasoning was since dseries are mostly the same build or i could be wrong and it does matter that much

 

depends what you are buying. most things are the same, some are differant between 1.5 and 1.6. also, there are small differances between years of single cam.