I have another question about pulleys. So ill start over. I have a stock motor with a comptech s/c and stock pulley. I have an ap1 by the way. I want to upgrade my pulley to a smaller one but need to know if i can do so without changing the injectors or needing some type of engine management. The science of speed recommends different injectors and ems for even the 4" pulley which is suppose to be 8psi on the ap1 but a couple of people said it would be fine with my stock setup. What do you guys think. Do you think ill be fine?

 

I wouldn't chance it. I scored my #1 and #4 cylinders with a 4" pulley and VAFCII. It's my fault for not making sure the previous owner had it properly tuned. You will be very close to maxing out the stock injectors. It might be possible to run safe, but get it on a dyno and see what your A/F is like and if the FMU can handle it.

I am having 550cc injectors and a AEM F/IC installed later this week. IMO, spend the extra $$ on some form of EMS and injectors, it will be much cheaper in the long run than a new motor.