Quote Originally Posted by differentK View Post
welcome to the family- its a small one. I never played with a JRSC A3 so i don't know what pulley sizes turn out what boost- but if you are looking to make over 9psi, I would suggest some sort of cooling. Meth injection is great, I run a 3gal AIS kit myself. I would start with the 4.0 pulley, use the calibration in kpro, get it running and see how you like it. just remember, more boost more cooling... these blowers create a lot of heat so if you want your engine to last you need to address that.
The 4.4 pulley is 5psi and for the street kit. The 4.0 is 8psi and for the race version. If recall JR had not recommended the use of anything smaller than 3.8 as it would overdrive the bearings in the SC but nobody has ever reported this being an issue.