The 86-87 d16a1 pistons you have are different from the 88-89 d16a1 pistons. Those pistons have a flat top, the 88-89 are domed. You will raise compression with them, supposedly about 11.6:1, but don't take my word for it though. Of course, you would yield higher compression with the 88-89 d16a1 pistons.