Stock number 2023 same as 5534?

 

Yes. The 2023 was their old stock number; 5534 is the new one.

 

I don't know why they do that as it seems to just create confusion in the marketplace.

Do you think running the 7's instead of the 6's might be causing the little stumble I have at idle?

 

E85 burns quite a bit cooler than gas, so you could definitely try running the 6's and see if that helps. If your keeping the boost below 18psi, the Bosch Supers in standard heat-range are a good choice. Those tend to have a little better idle than the NGKs (but they don't like high-boost).