1. With putting a cai on it's a good idea to have a custom tow tune.
2. Why run any risk of running lean? Although the K+N is one of the least agressive cai's on the market. It should be ok.
3. Cat back exhaust will not change a thing.
4. 87-89 are grouped together with the same afr tables and timing curves.
$.08 difference? In SD right now 89 is $.15 cheaper than 87.
5. Elevation changes should be ok.
The tables should account for them.
6. Sales? Haven't heard of anything yet.
Take care!
