Rock auto lists injectors for my 87 but there are two different ones a center and an offset guide. Is there a difference between them other than the guide?

 

Mazda changed the electrical impedance of the RX7 injectors going from S4 to S5. You need to check the manufacture date of your car based on the sticker on the door. If it were manufactured in in 87.5 it is an 88 model year. From 86-87, Mazda used low impedance injectors. From 88-91, Mazda use high impedance injectors. They switched over from low to high during mid year 87 or 87.5. Here's a link with more details: https://www.nopistons.com/2nd-genera...jectors-39111/