GT4 Zed - I appreciate your long post but I'm still not sure what you are getting at...
In short, (correct me if I am wrong) ...
With the UTEC connected Dave is throwing a CEL with a misfire (regardless of the S/C belt connected or not?) So I believe that things like the 1 step colder plugs arent going to have alot of impact with what essentially is a N/A engine.
Has the car been run, w/out the SC connected on the OEM ECU (i.e. removing the UTEC)?I'm not sure how happy the ECU would be with the increased injectors and higher capacity rails but I am under the impression the fuelling would be driven by the ECU and not by the rails and pumps, additional items allows threshold to be higher via a remap, i.e. not maxing out capacity? Perhaps someone can confirm?
The final thing is that as no internals have changed, so in my opinion it can only be 1 of two things, UTEC or rails.
Dave just a thought, obviously you had an Uprev flashed on to the ECU. This isn't complicating the piggyback of the UTEC is it?
Dan