I am one of the many that had the blower and reflash before the X-1. The problems start when u drop a pulley size, when I did I had the X-1 installed and it showed my 425cc's were maxxed out at 95% IDC from adding the URD 2.825" pulley but my A/F's were dead on.Eventually the stock pumps sock would get clogged enough to give me problems and because I got a sweet deal on the 668cc injectors I went with them instead of spending $625 for a 7th. The 7th gives enough fuel to run the smaller 2.7" pulley also.
I eventually got the 7th injector for a couple of reasons. (1) being if I choose to run E85 I can and (2) the 7th actually adds a small amount of power because it's injecting fuel before the blower thus cooling the air even more and also helps better seal the blower blades creating a wee bit more boost. When summer came I could feel I big improvement in power over last summer from the 7th cooling the charge. In the summer u get heat soak and the 7th makes that all disappear making it feel like a 20hp increase.