I need to knowif there is a difference in intake manifolds, throtle body, injectors, etc, between a 1990 1.5 L and a 1991 1.6 L Si???

 

All I can say is size, however, why do you want to know, planning on upgrading your 1.5? Well, with the equipment off of the 1.6 you are wasting your money. They only improvements you will notice is the psycological feeling of having a bigger intake.