I have also ran a 12.1 with stock injectors at a track that was at 3000' of elevation, and that was with a single stock CP3. The difference is I was running twin turbos and a lot more than 2600 uS pulse width. I never said you can't run 12.1 with stock injectors. I said you can't make that much power with stock injectors and 2600 pulse without doing something stupid with fuel pressure.That's not necessarily true. I saw a certain member who's name shall not be mentioned run a 12.1 on stock injectors. This was at rmr raceway which is 4400'. Full weight ccsb. But........he had dual fuelers.
Do you actually want 550 hp, or do you just want to be able to tell people you have 550 hp?What elevation track are you at? I'm sick of people telling me where my truck "should be at" or "isn't". I made 515 on my stock trans not sure on the pulse, 550 on a 2600 us pulse, and 596 with a 2950 pulse, all on different dyno sessions. Have you ever ran at RMR?